kkobashi - 6:58 am on Jun 7, 2006 (gmt 0)

To answer your own question, do this:

Check the source on the page you put the ads on. If the ad code is missing, then it was filtered by Blogger. You will then need to put your blog somewhere else.

If the ad code exists in the source of the page, then call up YPN customer support and let them troubleshoot the issue.