unity3.5 iOS build errors

Hi, I am using unity3.5 pro + iPhone to compile a simple test project but have the following errors when I tried to run the built project in xCode3.2:

   "_OBJC_CLASS_$_GKAchievement", referenced from:
 
       objc-class-ref-to-GKAchievement in libiPhone-lib.a(iPhoneGameCenter.o)
 
      (maybe you meant: _OBJC_CLASS_$_GKAchievementViewController)
 
   "_OBJC_CLASS_$_GKAchievementDescription", referenced from:
 
       objc-class-ref-to-GKAchievementDescription in libiPhone-lib.a(iPhoneGameCenter.o)
 
   "_ADBannerContentSizeIdentifierLandscape", referenced from:
 
       _ADBannerContentSizeIdentifierLandscape$non_lazy_ptr in libiPhone-lib.a(iAd.o)
 
      (maybe you meant: _ADBannerContentSizeIdentifierLandscape$non_lazy_ptr)
 
   "_ADBannerContentSizeIdentifierPortrait", referenced from:
 
       _ADBannerContentSizeIdentifierPortrait$non_lazy_ptr in libiPhone-lib.a(iAd.o)

I did not use any GameCenter or iAd in my unity project, and both GameKit.framework and iAd.framework were included in the unity-iPhone built project. I haven't found any post on the same issue. Anybody knows the answer?

BTW, I am using XCode3.2, and selected iOS 4.0 as the "Target iOS Version" in unity's "player setting", although my iPad uses iOS 5.1.

Thanks in advance!

Jack