Why are my adult corn snakes not eating?

One is four foot and one is five foot. They live in the same tank and i feed them indavidually in a separate tank and have never had a problem until four weeks ago. i feed them weanling rats usually every 2-3 weeks ttwo weeks ago i went to feed them and they refused to eat. They would kill the rats then loose intrest.i have tried feeding them in their housing tank and i have tried dangling it infront of them and they strike then drop it and loose inttrest again. i feed them white wenlings and thats how its always been since they were raised. There is no history of food refusal. I tried to feed them 2 weeks later and they did the same thing. why wont they eat?