The dealer has to program the computer to enable to cruise feature. It won't just learn it on its own. It never ceases to amaze me how incompetent and un-knowledgeable many dealers are. Don't even get me started about the parts department. LOL My gf's father went to 5 dealers trying to get a spare tire key, and not a one of them had a clue.
Also, did you install the sliding contact assembly from the cruise equipped truck the steering wheel came from? You need both pieces for it to work.