There are quite a number of other things that could prompt this behavior. I agree with checking your temps to make sure they are accurate. You also need to make sure your enclosure is big enough for him. As dragons get bigger, there is more surface area that absorbs heat. If they are in a small enclosure and can't get away from that heat when they need to, they will essentially "bake" to death. Another thing to look at is the size of the crickets you are giving him. There is a point with dragons when the size ratio of the dragon to the prey is too great and they will ignore the prey because it is too much effort to catch something soo small. Also, what are you feeding your feeders and do you dust them? Dehydration is another thing that will cause dragons to stop eating. Make sure he is drinking water. Just a few things to look at.