Sweetsusieg, is actually incorrect. Bearded dragons NEED ABSOLUTELY NEED fresh veggies. They do prefer live, moving food, but they will not be a healthy BD if not fed veggies.
What have you been offering? Have you tried something other than what you normally offer? How old is the BD?
Try spring mix lettuces, carrots, squash, strawberries, mango, etc. You want to promote a varied diet in order to ensure proper nutrition.