There are a number of reasons why a campaign is not visible on your site. Some reasons have to do with the way the Ad Unit functions, or there could be a technical problem that needs to be addressed. If you don't find your solution in the articles below, please contact us for technical support. 

How are Sites approved? How long does site approval take?

Why was my Site rejected?

Technical issues:

Can I publish an Ad Unit on a Mobile App?

Why doesn't my Site appear in the Sites section after I embed an Ad Unit?