I have observe that yahoo is crawling everyday but it won’t generates hits or maybe if there is then that I haven’t notice it at all. Does yahoo never returns us any hits?

Maybe Yahoo users are not interested in your website.

Maybe it's because you think there's only one search engine, so your pages don't get shown to Yahoo! users?

Plus a multitude of other reasons.

More people are using google as search engine, so you don't have to worry about this, just concentrate on what you are doing.