Adhoc Created on XCode 4 installs fine on iPad but not on iPhone. What could be wrong?

Here's what I have already tried:

1. I created adhoc with and without entitlement.plist. But this a开发者_开发问答dhoc installs fine on iPad but not on iPhone.

It gives "Code signing error".

What else should I check?

Thanks!

are you sure the phone is listed on the provisioning profile?