Also, remember variety is important. Maybe your little cham is bored of crickets. I would recommend trying some smaller crickets, and some different food items. All of my chameleons love hornworms and flies.
Sorry but you have it wrong on the size of the crickets. They need to be NO larger than the space between the chameleons eyes. A cricket the size of it;s head is way too big. What kind of chameleon are we talking about and are you sure it is that young? That is a pretty young baby.
If that cham is only 6 weeks old he can still be eating fruitflys. Try those and some small horns or silks. Then go back to crix and rotate food items. Crix can be 60% or so diet but try to mix em up and gutload. Have at least three nutritious fod itmes on hand at all times in case they get sick of something.