Have you tried to stimulate a poop? Mine will always poop 5 to 10 minutes after I take him out of his cage. I'm sure that's a "put me back!" thing. People report they poop after a good shower or after some extended (supervised) time in the sun.
You might try putting multiple feeders, including the beloved superworms, in his cage at once. Give him a cup with a couple of supers, a couple of crickets (I guess you should tear off a leg....gads, I hate that concept), maybe a roach or a phoenix worm....see what happens.
While those who've posted in this thread are anti-super, I know I've been lectured by very informed people (Brad Ramsey jumps to mind)over my inability to feed supers to my chameleon. I've been told that it is as good if not a better basic feeder than crickets. They take well to gutloading, perhaps better than crickets.
They scare the willies out of me, but if you can handle them and gutload them correctly, then I see no reason to deny your chameleon food longer than you are comfortable doing so.