Punish if: He beeps for no reason or he won't eat when he is hungry. No-reason beeping is if he does not have all hearts out on one or two meters, he is not sick, he is not sleeping.
Praise if: He has his back to you. In the instructions, it looks like it is if he turns black, but that is because it is a Gozarutchi who has his back to you.*ninja guy*
Then again, you say he never does? If you have the sound off most of the time or if you change the time, you can miss a lot of oppurtunities to Punish him.
I think this should help. PM me if you need more information.