iAd strange console "Unhandled error"

Question

I'm seeing in the console:

"Unhandled error (no delegate or delegate does not implement didFailToReceiveAdWithError:):"

Although didFailToReceiveAdWithError is being invoked (I can see that with check points and in the console log)

Does someone has any reasonable explanation? It's like it's working and not working all in the same time. I'm not using IB for the adview, and have added it programmatically and have set the adview.delegate = self. I'm also using three20 in this project if that changes anything.

It's like sometimes he knows who's his delegate and sometime not...