The FAQ says: Running Co-op On Multiple Sites And Subdomains What If You Want To Add Co-op To More Than One Site? That's fine! Great idea because the bigger the network, the wider the spread of our ads. However, there are some rules you have to follow: You can only have one account per domain! This means you can not sign up again with a subdomain or a subfolder as your Base-URL. You need one account for each domain! After signing up your second/third/fourth/etc. website in new accounts you can consolidate (see Ad Management) all into one Master account for ease of inventory management. So in other words if I want to use subdomains, I can use only one. I will not be able to create multiple subdomain accounts from the same main domain name? Too bad! My best PR and subpages are located under subdomains...
The other option would be to use http://yourdomain.com as the base URL, and run ads on all sub-domains.
I've tried but It's not validating, google is showing url's that I have deleted over an year ago..that's why I'm using one subdomain...and anyways the main domain name does not contain too many pages besides my subdomains sometimes having over 200 subpages because this is a travel related site.. Too bad I can't participate with the rest in the network :-(
go to google and manually ask them to delete the pages, should happen rather quickly, then you won't have a problem running the yourdomain.com