It is showing public ads because there is no ads for the keywords in your webpage, you may want to try different keywords and see whether that solve the problem.
Why don't you try placement things, I think it will help you out...choice your own domain to advertise. Alam
"Your pages are displaying Public Service Advertisements (PSAs) because you haven't yet verified your PIN" this is what i saw today in my adsense account. If you dont have this message, but still have only public ads, you may want to place privacy policy page on your web site. Read more about it in google support forums.