I am updating an app with iAd. The current version has iAd, and everything works great. But the changes have been substantial enough that I want to test the ads again before I
I dealt with the "Unknown error" message for close to 9 hours. For me, my iPod touch had reset itself to 1970. I accidentally let the battery drain and the time & date got set back. I never bothered to set it back because I don't use that often. Once I set the date to the current date, that and other things began to work correctly (in-app purchases were also screwed up).
Make sure you have set the ADBannerView delegate.