Allen does look a bit dehydrated.
Some chams always need several minutes of misting before they will drink. You can also try the shower method to hydrate him quickly.
This is from the forum resources:
"Shower - Another method of providing water, especially to dehydrated chameleons, is by using a shower. Place a large plant in the tub, aim the shower head against the wall, and run the water so that only a fine mist reaches the chameleon. The water should be room temperature (not hot!). They may drink for up to 30 minutes. Make sure to supervise your chameleon at all times while using this method."