SEO SearchTerms Tagging 2 plugin not working

I installed the plugin on wordpress 3.2.1. The problem is that almost all incoming searches goes under the last post, which is appearing as a first post on the home page, though it is not ranking for these searches. Only very few searches goes under the right blog posts.

Any idea why this is happening?

http://wordpress.org/extend/plugins/searchterms-tagging-2/