Hi there, guys plz help me with this.
I don't know what cause my problem. I got this error massage.
Any clues what can be the problem?

Error page:
( ! ) Fatal error: Call to a member function get() on a non-object in /data/www/ablux.pl/html/modules/mod_mainmenu/helper.php on line 134
Call Stack
# Time Memory Function Location
1 0.0001 95928 {main}( ) ../index.php:0
2 0.1876 6197096 JSite->render( ) ../index.php:79
3 0.1878 6197096 JDocumentHTML->render( ) ../application.php:168
4 0.1957 6279384 JDocumentHTML->_parseTemplate( ) ../html.php:249
5 0.3066 15190840 JDocumentHTML->getBuffer( ) ../html.php:386
6 0.3067 15190840 JDocumentRendererModules->render( ) ../html.php:190
7 0.3067 15190840 JDocumentRendererModule->render( ) ../modules.php:41
8 0.3076 15199120 JModuleHelper->renderModule( ) ../module.php:84
9 0.3102 15321008 require( '/data/www/ablux.pl/html/modules/mod_mainmenu/mod_mainmenu.php' ) ../helper.php:173
10 0.3115 15347528 require( '/data/www/ablux.pl/html/modules/mod_mainmenu/tmpl/default.php' ) ../mod_mainmenu.php:42
11 0.3115 15347528 modMainMenuHelper->render( ) ../default.php:82
12 0.3115 15347800 modMainMenuHelper->getXML( ) ../helper.php:156
13 0.3806 15720168 JSimpleXMLElement->map( ) ../helper.php:127
14 0.3806 15720168 {main}( ) ../simplexml.php:0
15 0.3806 15720264 modMainMenuHelper::render( ) ../default.php:82


helper.php looks like this:

PHP Code:

<?php
/**
* @version        $Id: helper.php 12694 2009-09-11 21:03:02Z ian $
* @package        Joomla
* @copyright    Copyright (C) 2005 - 2008 Open Source Matters. All rights reserved.
* @license        GNU/GPL, see LICENSE.php
* Joomla! is free software. This version may have been modified pursuant
* to the GNU General Public License, and as distributed it includes or
* is derivative of works licensed under the GNU General Public License or
* other free or open source software licenses.
* See COPYRIGHT.php for copyright notices and details.
*/

// no direct access
defined('_JEXEC') or die('Restricted access');


jimport('joomla.base.tree');
jimport('joomla.utilities.simplexml');

/**
 * mod_mainmenu Helper class
 *
 * @static
 * @package        Joomla
 * @subpackage    Menus
 * @since        1.5
 */
class modMainMenuHelper
{
    function buildXML($params)
    {
        $menu = new JMenuTree($params);
        $items = &JSite::getMenu();

        // Get Menu Items
        $rows = $items->getItems('menutype', $params->get('menutype'));
        $maxdepth = $params->get('maxdepth',10);

        // Build Menu Tree root down (orphan proof - child might have lower id than parent)
        $user =& JFactory::getUser();
        $ids = array();
        $ids[0] = true;
        $last = null;
        $unresolved = array();
        // pop the first item until the array is empty if there is any item
        if ( is_array($rows)) {
            while (count($rows) && !is_null($row = array_shift($rows)))
            {
                if (array_key_exists($row->parent, $ids)) {
                    $row->ionly = $params->get('menu_images_link');
                    $menu->addNode($params, $row);

                    // record loaded parents
                    $ids[$row->id] = true;
                } else {
                    // no parent yet so push item to back of list
                    // SAM: But if the key isn't in the list and we dont _add_ this is infinite, so check the unresolved queue
                    if(!array_key_exists($row->id, $unresolved) || $unresolved[$row->id] < $maxdepth) {
                        array_push($rows, $row);
                        // so let us do max $maxdepth passes
                        // TODO: Put a time check in this loop in case we get too close to the PHP timeout
                        if(!isset($unresolved[$row->id])) $unresolved[$row->id] = 1;
                        else $unresolved[$row->id]++;
                    }
                }
            }
        }
        return $menu->toXML();
    }

    function &getXML($type, &$params, $decorator)
    {
        static $xmls;

        if (!isset($xmls[$type])) {
            $cache =& JFactory::getCache('mod_mainmenu');
            $string = $cache->call(array('modMainMenuHelper', 'buildXML'), $params);
            $xmls[$type] = $string;
        }

        // Get document
        $xml = JFactory::getXMLParser('Simple');
        $xml->loadString($xmls[$type]);
        $doc = &$xml->document;

        $menu    = &JSite::getMenu();
        $active    = $menu->getActive();
        $start    = $params->get('startLevel');
        $end    = $params->get('endLevel');
        $sChild    = $params->get('showAllChildren');
        $path    = array();

        // Get subtree
        if ($start)
        {
            $found = false;
            $root = true;
            if(!isset($active)){
                $doc = false;
            }
            else{
                $path = $active->tree;
                for ($i=0,$n=count($path);$i<$n;$i++)
                {
                    foreach ($doc->children() as $child)
                    {
                        if ($child->attributes('id') == $path[$i]) {
                            $doc = &$child->ul[0];
                            $root = false;
                            break;
                        }
                    }

                    if ($i == $start-1) {
                        $found = true;
                        break;
                    }
                }
                if ((!is_a($doc, 'JSimpleXMLElement')) || (!$found) || ($root)) {
                    $doc = false;
                }
            }
        }

        if ($doc && is_callable($decorator)) {
            $doc->map($decorator, array('end'=>$end, 'children'=>$sChild));
        }
        return $doc;
    }

    function render(&$params, $callback)
    {
        switch ( $params->get( 'menu_style', 'list' ) )
        {
            case 'list_flat' :
                // Include the legacy library file
                require_once(dirname(__FILE__).DS.'legacy.php');
                mosShowHFMenu($params, 1);
                break;

            case 'horiz_flat' :
                // Include the legacy library file
                require_once(dirname(__FILE__).DS.'legacy.php');
                mosShowHFMenu($params, 0);
                break;

            case 'vert_indent' :
                // Include the legacy library file
                require_once(dirname(__FILE__).DS.'legacy.php');
                mosShowVIMenu($params);
                break;

            default :
                // Include the new menu class
                $xml = modMainMenuHelper::getXML($params->get('menutype'), $params, $callback);
                if ($xml) {
                    $class = $params->get('class_sfx');
                    $xml->addAttribute('class', 'menu'.$class);
                    if ($tagId = $params->get('tag_id')) {
                        $xml->addAttribute('id', $tagId);
                    }

                    $result = JFilterOutput::ampReplace($xml->toString((bool)$params->get('show_whitespace')));
                    $result = str_replace(array('<ul/>', '<ul />'), '', $result);
                    echo $result;
                }
                break;
        }
    }
}

/**
 * Main Menu Tree Class.
 *
 * @package        Joomla
 * @subpackage    Menus
 * @since        1.5
 */
class JMenuTree extends JTree
{
    /**
     * Node/Id Hash for quickly handling node additions to the tree.
     */
    var $_nodeHash = array();

    /**
     * Menu parameters
     */
    var $_params = null;

    /**
     * Menu parameters
     */
    var $_buffer = null;

    function __construct(&$params)
    {
        $this->_params        =& $params;
        $this->_root        = new JMenuNode(0, 'ROOT');
        $this->_nodeHash[0]    =& $this->_root;
        $this->_current        =& $this->_root;
    }

    function addNode(&$params, $item)
    {
        // Get menu item data
        $data = $this->_getItemData($params, $item);

        // Create the node and add it
        $node = new JMenuNode($item->id, $item->name, $item->access, $data);

        if (isset($item->mid)) {
            $nid = $item->mid;
        } else {
            $nid = $item->id;
        }
        $this->_nodeHash[$nid] =& $node;
        $this->_current =& $this->_nodeHash[$item->parent];

        if ($item->type == 'menulink' && !empty($item->query['Itemid'])) {
            $node->mid = $item->query['Itemid'];
        }

        if ($this->_current) {
            $this->addChild($node, true);
        } else {
            // sanity check
            JError::raiseError( 500, 'Orphan Error. Could not find parent for Item '.$item->id );
        }
    }

    function toXML()
    {
        // Initialize variables
        $this->_current =& $this->_root;

        // Recurse through children if they exist
        while ($this->_current->hasChildren())
        {
            $this->_buffer .= '<ul>';
            foreach ($this->_current->getChildren() as $child)
            {
                $this->_current = & $child;
                $this->_getLevelXML(0);
            }
            $this->_buffer .= '</ul>';
        }
        if($this->_buffer == '') { $this->_buffer = '<ul />'; }
        return $this->_buffer;
    }

    function _getLevelXML($depth)
    {
        $depth++;

        // Start the item
        $rel = (!empty($this->_current->mid)) ? ' rel="'.$this->_current->mid.'"' : '';
        $this->_buffer .= '<li access="'.$this->_current->access.'" level="'.$depth.'" id="'.$this->_current->id.'"'.$rel.'>';

        // Append item data
        $this->_buffer .= $this->_current->link;

        // Recurse through item's children if they exist
        while ($this->_current->hasChildren())
        {
            $this->_buffer .= '<ul>';
            foreach ($this->_current->getChildren() as $child)
            {
                $this->_current = & $child;
                $this->_getLevelXML($depth);
            }
            $this->_buffer .= '</ul>';
        }

        // Finish the item
        $this->_buffer .= '</li>';
    }

    function _getItemData(&$params, $item)
    {
        $data = null;

        // Menu Link is a special type that is a link to another item
        if ($item->type == 'menulink')
        {
            $menu = &JSite::getMenu();
            if ($newItem = $menu->getItem($item->query['Itemid'])) {
                $tmp = clone($newItem);
                $tmp->name     = '<span><![CDATA['.$item->name.']]></span>';
                $tmp->mid     = $item->id;
                $tmp->parent = $item->parent;
            } else {
                return false;
            }
        } else {
            $tmp = clone($item);
            $tmp->name = '<span><![CDATA['.$item->name.']]></span>';
        }

        $iParams = new JParameter($tmp->params);
        if ($params->get('menu_images') && $iParams->get('menu_image') && $iParams->get('menu_image') != -1) {
            switch ($params->get('menu_images_align', 0)){
                case 0 : 
                $imgalign='align="left"';
                break;
                
                case 1 :
                $imgalign='align="right"';
                break;
                
                default :
                $imgalign='';
                break;
            }
                
            
            $image = '<img src="'.JURI::base(true).'/images/stories/'.$iParams->get('menu_image').'" '.$imgalign.' alt="'.$item->alias.'" />';
            if($tmp->ionly){
                 $tmp->name = null;
             }
        } else {
            $image = null;
        }
        switch ($tmp->type)
        {
            case 'separator' :
                return '<span class="separator">'.$image.$tmp->name.'</span>';
                break;

            case 'url' :
                if ((strpos($tmp->link, 'index.php?') === 0) && (strpos($tmp->link, 'Itemid=') === false)) {
                    $tmp->url = $tmp->link.'&amp;Itemid='.$tmp->id;
                } else {
                    $tmp->url = $tmp->link;
                }
                break;

            default :
                $router = JSite::getRouter();
                $tmp->url = $router->getMode() == JROUTER_MODE_SEF ? 'index.php?Itemid='.$tmp->id : $tmp->link.'&Itemid='.$tmp->id;
                break;
        }

        // Print a link if it exists
        if ($tmp->url != null)
        {
            // Handle SSL links
            $iSecure = $iParams->def('secure', 0);
            if ($tmp->home == 1) {
                $tmp->url = JURI::base();
            } elseif (strcasecmp(substr($tmp->url, 0, 4), 'http') && (strpos($tmp->link, 'index.php?') !== false)) {
                $tmp->url = JRoute::_($tmp->url, true, $iSecure);
            } else {
                $tmp->url = str_replace('&', '&amp;', $tmp->url);
            }

            switch ($tmp->browserNav)
            {
                default:
                case 0:
                    // _top
                    $data = '<a href="'.$tmp->url.'">'.$image.$tmp->name.'</a>';
                    break;
                case 1:
                    // _blank
                    $data = '<a href="'.$tmp->url.'" target="_blank">'.$image.$tmp->name.'</a>';
                    break;
                case 2:
                    // window.open
                    $attribs = 'toolbar=no,location=no,status=no,menubar=no,scrollbars=yes,resizable=yes,'.$this->_params->get('window_open');

                    // hrm...this is a bit dickey
                    $link = str_replace('index.php', 'index2.php', $tmp->url);
                    $data = '<a href="'.$link.'" onclick="window.open(this.href,\'targetWindow\',\''.$attribs.'\');return false;">'.$image.$tmp->name.'</a>';
                    break;
            }
        } else {
            $data = '<a>'.$image.$tmp->name.'</a>';
        }

        return $data;
    }
}

/**
 * Main Menu Tree Node Class.
 *
 * @package        Joomla
 * @subpackage    Menus
 * @since        1.5
 */
class JMenuNode extends JNode
{
    /**
     * Node Title
     */
    var $title = null;

    /**
     * Node Link
     */
    var $link = null;

    /**
     * CSS Class for node
     */
    var $class = null;

    function __construct($id, $title, $access = null, $link = null, $class = null)
    {
        $this->id        = $id;
        $this->title    = $title;
        $this->access    = $access;
        $this->link        = $link;
        $this->class    = $class;
    }
}

Any ideas guys what, can be a problem here.
Some times the site works fine, but sometimes i get above mentioned error

please help me (

Next time use the PHP bbcode and indicate which line the error is on.

It looks like you are calling render with a non-object as the first parameter. The definition for render is in the code you posted, but no calls. Going by your stack trace it looks like the call that is causing the problem is on line 79 of index.php

Hello, i'm sorry for that.
here it's the index file which refers to render

PHP Code:

<?php
/**
* @version        $Id: index.php 11407 2009-01-09 17:23:42Z willebil $
* @package        Joomla
* @copyright    Copyright (C) 2005 - 2009 Open Source Matters. All rights reserved.
* @license        GNU/GPL, see LICENSE.php
* Joomla! is free software. This version may have been modified pursuant
* to the GNU General Public License, and as distributed it includes or
* is derivative of works licensed under the GNU General Public License or
* other free or open source software licenses.
* See COPYRIGHT.php for copyright notices and details.
*/

// Set flag that this is a parent file
define( '_JEXEC', 1 );

define('JPATH_BASE', dirname(__FILE__) );

define( 'DS', DIRECTORY_SEPARATOR );

require_once ( JPATH_BASE .DS.'includes'.DS.'defines.php' );
require_once ( JPATH_BASE .DS.'includes'.DS.'framework.php' );

JDEBUG ? $_PROFILER->mark( 'afterLoad' ) : null;

/**
 * CREATE THE APPLICATION
 *
 * NOTE :
 */
$mainframe =& JFactory::getApplication('site');

/**
 * INITIALISE THE APPLICATION
 *
 * NOTE :
 */
// set the language
$mainframe->initialise();

JPluginHelper::importPlugin('system');

// trigger the onAfterInitialise events
JDEBUG ? $_PROFILER->mark('afterInitialise') : null;
$mainframe->triggerEvent('onAfterInitialise');

/**
 * ROUTE THE APPLICATION
 *
 * NOTE :
 */
$mainframe->route();

// authorization
$Itemid = JRequest::getInt( 'Itemid');
$mainframe->authorize($Itemid);

// trigger the onAfterRoute events
JDEBUG ? $_PROFILER->mark('afterRoute') : null;
$mainframe->triggerEvent('onAfterRoute');

/**
 * DISPATCH THE APPLICATION
 *
 * NOTE :
 */
$option = JRequest::getCmd('option');
$mainframe->dispatch($option);

// trigger the onAfterDispatch events
JDEBUG ? $_PROFILER->mark('afterDispatch') : null;
$mainframe->triggerEvent('onAfterDispatch');

/**
 * RENDER  THE APPLICATION
 *
 * NOTE :
 */
$mainframe->render();       // here is the 79 line

// trigger the onAfterRender events
JDEBUG ? $_PROFILER->mark('afterRender') : null;
$mainframe->triggerEvent('onAfterRender');

/**
 * RETURN THE RESPONSE
 */
echo JResponse::toString($mainframe->getCfg('gzip'));

Can i change this line somehow to get the fix address, or something to avoid my problem?

PHP Code:

$mainframe =& JFactory::getApplication('site'); 


PHP Code:

$mainframe->render(); 


render has to take two parameters; you are calling it with none. Unfortunately I can't tell from the code or comments what you should be passing to render in this case.

I see, can you tell me please why the site is working sometimes, and sometimes not?

If there is a problem with this files, the internet site should not work all time.

Am i right?

Can it be something wrong with the serwer side?