How long have you had the chameleon?

What is the temperature in the cage?

What brand and type (compact, long linear, spiral) UVB light are you using?

What size is the chameleon and what size are the insects being offered to it? Is it drinking? How long has it been since it stopped eating?

Vitamin A deficiencies are less common in veileds IMHO....but vitamin A and D3 and calcium and phos. all need to be in balance.