byuboundHow old is it? Those get super hard to take if they aren't really young. Also, how do you feed it? I've heard that people who drop in food by hand can have trouble, as they associate the hand with hunting. You could try tongs if you are doing this. Personally I have never had one though, so this is all from others experiences pretty much. Good luck!
Geckos might be a little different, but when I had pythons I would always have a separate container that I would use strictly for feeding. As soon as I'd drop a snake in the feed cage, it would immediately coil and ready itself for a strike. It might be worth a try.
Also, if the tank is too small, your gecko might feel like it doesn't have a proper 'hideout' which could make him rather protective of his space.