Are you feeding frozen/thawed or live? I agree with Zincubis- we need a bit more information. Do you have a thermostat to regulate your UTH?
When I tried to feed my new BP she wouldn't take it off the tongs (f/t). She actually seemed afraid of the mouse and curled up into a tight ball. I left it in the enclosure and gave her some space. 10 minutes later I went in to check on her and the mouse was gone! Your snake might just be a shy eater like mine. If you haven't yet, try to leave his dinner in the enclosure for a few minutes and see if that helps.