Our wonderful 7-month-old Sheltie puppy, Fainly, whom we trained to use a doorbell to go outside for pottying (with our accompaniment to his potty area) cannot seem to learn now to transition to using a doggie door by himself. We've been trying for a week or so, and he isn't understanding. He's not afraid of the door, but he still uses the doorbell to tell us he has to go (and for other things he wants to do or needs) so that the doorbell is ringing frequently, and he won't use the doggie door unless we are there and go out with him to his new potty area, which is at the other end of the house and downstairs from the former area. We didn't have a choice in where to put the door. When we're there and go out the human-size door next to the doggie door he happily goes out his door and uses the potty area. To complicate matters he has inflammatory bowel syndrome and has diarrhea at times. We're concerned that if we remove the doorbell he'll start going on the carpet. Help! Any of your sage advice will be appreciated.Thank you!