Specific sites ads: why my ads are not displayed?

Hello,
I have several campaigns targeting specific sites, some of them are working pretty well, others I am simply unable to have my ads displayed! I really don't know why, no matter how much budget or bid I give to those campaigns I am unable to have my ads served and displayed. Any idea?

Any help is really appreciated, thank you in advance.

Sincerely,
Fab.

Assuming that you bid high enough, I see two possible reasons :
- your new ads need a manual approval by Google employees for some reason (you can call or email them to push);
- your URL is in the list of filtered URL's at the target site.

Jean-Luc

Thank you for your reply.

Well, I don't think your first reason is the case since I created those campaigns already more than one month ago. Most likely is the second one. I didn't know that they can block ads for certain URLs. But shouldn't GoogleAd tell me that? If my URL is blocked I should know it.

Thank you for your thoughts.

Sincerely,
Fabrizio