iAd not displaying on XCode 4.0.1

I am trying to add iAds in my existing Iphone application. I have implemented everything by following: http://www.raywenderlich.com/1371/how-to-integrate-iad-into-your-iphone-app but the ads do not show up in my app. I am using XCode 4开发者_开发百科.0.1 and iOS 4.3.3.

I can't even run the example given on that link. When I run my existing code on XCode 3.x version everything works fine and ads show up correctly.

Can anyone tell me what's the problem with Xcode 4.0.1 version ?

Thanks.

I upgraded my XCode and it solved the issue. May be it was a bug with XCode