King snakes are great eaters. How big is it? How big is the mouse ur feeding it? I have an eastern king snake. I hold the mouse by the tail and he jus starts eating it. Maybe it isn't warm enough. Are u thawing it in water? If so make sure u thaw it in the bag so u dnt wash the smell away. Try diping it in chicken broth. Or pop a hole in the head so the snake smells the blood.. sounds nasty but it works.