I have an image host, lets call it www.imagehost.com and each page has 3 adsense ads on it. There is plenty of ads for whats on the page and I have never seen only 2 banner spot with ads and the rest with none. Now I just recently added another server to the mix and it is http://server2.imagehost.com and all I did was copy over my script and change the appropiate config files so it would work with the new subdomain. Now for some reason one one of the 3 banner spots fills with ads the other 2 are empty no matter how many itmes I've refreshed the page and no matter if the picture has been viewed 1000 times there is only 1 banner spot filled up. I have changed nothing no code or anything except the channel id and the domain its hosted on other then that the scripts are still the same and the same code is on the other original server www.imagehost.com I tried chaninging the channel id back with no luck either.
If it's brand new, it still may be evaluating the content. An alternative is that there are no relevant ads to your content, so they simply don't display if you have an alternate URL set. Are you sure that PSAs aren't being shown?