That is correct. Unfortunately, bishops sometimes make such mistakes. It is for the Vatican to straigthen matters - fortunately we have such an authority to correct such things, otherwise, we'd have mass confusion. By looking to the "official" teachings, we can separate the chaff from the wheat, even when the chaff is a bishop. There is only one bishop who is infallible, and ONLY when he is executing a particular, narrow office.
Brother of Christ
Do I dare.... :O)