Many woods used as substrates contain oils that are toxic to the chameleon...and with colored ones I would worry about dyes too. There is also the danger of the chameleon ingesting some of the substrate so its better IMHO not to use a substrate.
What brand and type (long linear tube or compact) UVB light do you have on the cage? There should be no glass or plastic between the light and the chameleon. Exposure to UVB allows the chameleon to produce D3 which allows it to use the calcium in its diet.
Its important to dust the insects at most feedings before feeding them to the chameleon with a phos.-free calcium powder at most feedings to make up for the poor ratio of calcium to phos. found in most feeder insects.
I also dust twice a month with a vitamin powder that contains a beta carotene source of vitamin A. Beta carotene won't build up in the system like preformed vitamin A will, but there is controversy as to whether any/all chameleons can convert the beta carotene so some people give a little preformed vitamin A once in a while. Excess preformed vitamin A can prevent the D3 from doing its job and lead to MBD...so don't overdo it.
I dust twice a month with a phos.-free Calcium/D3 powder too. D3 from supplements can build up in the system...so go easy on it.
Gutloading and feeding your insects a nutritious diet also helps your chameleon. Crickets can be fed a variety of greens (dandelion, kale, collards, endive, escarole, mustard greens, etc.) and veggies (carrots, squash, sweet potato, sweet red pepper, celery leaves, etc.)
Appropriate basking temperature helps with digestion so it plays a part in nutrient absorption. A baby only needs a basking temperature in the low 80's F while an adult can take it into the high 80's or low 90's F.
I have always used glass cages with screen lids for baby veileds and have had no problem with the reflections or the ventilation. You do have to make sure that no water lays stagnant on the floor of the cage though.
If the temperatures are too low the chameleon might not eat. Some of them take a few days to settle in as well. Is it pooping? (I hope its not impacted from ingesting any of the substrate.)
