Have you tried other feeders as well? Hornworms are fantastic, our chams go insane for them! The only thing is they do grow very fast, so if you order them, start out with just a few small ones then go from there. Butterworms are also great to use and need no care at all, just stick them in the fridge between feedings.
How big would you say your cham is from nose to vent (butt)?