Some types of worms emit an unpleasant odor, what were the worms marked as at the store, or did you collect them yourself?
I had a group of Salamandra salamandra that would relish worms when I first got them, but for whatever reason they lost interest after only a few feedings of crickets. Perhaps the fast movements of crickets are more attractive to them as a predator? It's cases like this I really wish I could read salamander minds.