IAD Test ads dont work in 4.2 or 4.3 on device or simulator

I cant seem to make the test a开发者_StackOverflow中文版ds work for anything other than 4.1 or 4.0 in the simulator. I downloaded the iAdSuite sample code from apple, and still can't get it to work under 4.3/4.2. I don't think the problem is with my code. could there be anything else that could cause this error?

a) if you have questions whether your code is wrong...you should post your code

b) have you looked at the responses your iAd delegate is receiving? often times I receive 'no inventory available' even for test ads.