Forum Moderators: Robert Charlton & goodroi
PR is only part of the jigsaw to get ranked.
Is your site SEO friendly, are your pages keyphrase themed, or are they over optimized , what are your inbound link anchor texts... etc. etc.
Find some seo tools and get testing and tweaking.
having PR doesn't mean you will rank for terms.
It's totally wrong if you consider PR4 to be a high pagerank! :)
Pagerank is one of the major factors for search engine rankings indeed, but the number of required PR may be much higher for your targeted keyword(s).
I wish you best of luck and suggest you take a deep look at WebmasterWorld; you will find plenty of information to enhance your rankings through time.