Crate Training a Puppy?

I have a 12 week old puppy that poops in his cage every time we put him in there. It is never longer than 3 hours and as short as 30 minutes. We make sure that he only has enough room to turn around, that he has pooped and peed before he goes in, and he actually likes his cage. Does anyone have any ideas how to break him of this?

Thanks!