Well, don't give him the treat if he doesn't do the trick.
Have you tried holding the treat out in your closed hand? He should try nuzzling for the treat, and then pawing at it. Reward him for pawing at it, and gradually shift to a command (or open palm).
Thor wouldn't paw at my hand, so I had to teach him to paw at something else (treat ball). Then I tought him to paw stuff in general, and then I switched to my hand.