King Snake Won't Eat

[cyberunlimited]

I have a 3 year old King Snake. It won't eat anything but crickets. I've tried to starve it for a few weeks and then introduce the small mice. I even tried meal worms. I've tried everything that the people down at Petsmart told me to do and it refuses to eat, except for the crickets. What else can I try and can it live on crickets. I'm afraid that it needs better nutrition.

Thanks.