I am monitoring a website that has been optimised over the past year. There are a number of very relevant keywords that are just not displaying the site in Google SERP's. I have today taken a very specific phrase from their keyword metatag and searched for this keyphrase within "". The result was that of only 635 results the website was not listed. The site is indexed and does appear for other keywords and phrases but there are a number that simply do not trigger any result. Any help or advice would be greatly appreciated.
The goole checks the quality and PR of sites when it start index. Its prefer the site with relevant category, PR of site and quality of site and you contents.