Tim has a very useful post for those of you who are rotating Adsense and YPN ads on your site (ie having each ad program show up on every second impression.
He was having some problems with getting PSA ads on YPN and found that part of the problem was the fact he was rotating ads. He writes:
‘So the next logical question was why am I getting PSAs on YPN? After having a few of the YPN engineers look at my site they figured out the reason it was getting PSAs was because I was rotating pageviews between YPN ads and AdSense ads. Basically the YPN bot that crawls pages to determine the content was getting confused because the page content was constantly changing and the YPN ads were there one second and gone the next. So each time a YPN ad was displayed it triggered a new “content review” and PSAs would be displayed.’
To find the solution to the problem head over to his post at Rotating YPN and AdSense is a Bad Idea.