Whenever we have to do the brown bag or box (for our larger snakes) we put them in a closet, closed off and far away from everything else. Maybe this will help? How often are you checking on him? Our picky eater pastel has to be in a box, in a closet, on the other side of the house and left alone for almost three hours to eat. It's a pain, but at least he eats. If we open the box, the whole process seems like it has to start over.