Fresh imports are usually very dehydrated and immediately need rehydrating. Pedialite works very well. A drip cup works better than misting for many species. The dripping seems to attract immediate attention. Try outdoor caging in direct sun.
Sunshine works magic on chameleons.
Keep in mind the temperature requirements for the species your are working with at all times. During the summer for montane chameleons, try early morning sun, and avoid the hot mid day sun. You can find in the sunshine, an animal that is having trouble acclimating, will feed and drink. The next step is to collect a fresh fecal sample for testing at your local vet. This usually is a low cost test.