Why aren't Admob click callback delegate methods getting called?

Question

I'm integrating the latest version of the admob sdk (version 20100412) into my app.

The ads get displayed, but I need the app to make some changes when an ad is clicked and admob displays a full-screen browser. However, none of the callback methods (willPresentFullScreenModal, didPresentFullScreenModal, willDismissFullScreenModal, and didDismissFullScreenModal) are called, even though other delegate methods are.

Why aren't these callbacks being made? They were in the previous versions of the SDK, and the sample app doesn't use them, so it's no help.

EDIT: removed the double negative from the question title