I just wondering why ads displaying in my site are not related to the content of the pages of my site. All pages are rich text page... I tried to tweak each pages but still got the same result. What are the factor causing this problems?
You need relevant words at the top of the page, because that's what Gbot looks at. Then you need to look at your own page and refresh several times in a row to give G an opportunity to figure out what ads to run. If you still don't get some good ads, look at your text and figure out why G thinks it's being relevant, then delete the misleading text and try again.