I create a blog which is cache by google.but not show in keyword result. plz tell me what is the reason behind it.
Juned just because something is cached, doesn't mean it will be in top 1000 results of google for that keyphrase.
doing proper SEO is the solution for this problem. YOu have to optimize your site and promote it to show up in SERPs
Ya seo is to be done correctly, if the number competetors of your niche is so huge, you have to do hard work for seo and wait to see the increase in pagerank.
it is because your blog is not optimize properly and your blog is just new build quality backlink that will help you gain that ranking. getting index is good but search engine spider can not see relevancy to a certain keyword that your blog contain.