Was the pet store feeding him live in the brown paper bag or had they trained him to eat dead food already? Making the switch from live to dead prey items isn't automatic.

What are your cage temps? Temperature and security are the two single greatest factors when it comes to feeding. 82-84 on the cool side, 92-94 on the hot ... make sure there are hides on both sides that are small so your snake can cram itself up inside of them to feel secure.

Also, a good digital thermometer will give you a true read on your temps .... those plastic stick on things that the pet stores sell are garbage.

-adam