I had this issue after my certificate expired and was certain the keys were all good and in the right places. The step I was missing was deleting the profiles in the Provisioning Portal and recreating them. Don't trust that "renew" link - it looks like such a tempting shortcut, but it just didn't work for me!
So, for a fresh start, not only do you need to delete the keys and certificates from your Keychain, you need to wipe the contents of the Development and Distribution tabs under Provisioning.
