What kind of chameleon do you have ? And how are you measuring the humidity? How low is "really low" - and how long does it take after spraying does it take before it goes back to "really low"
I've used this small humidifier
http://www.amazon.com/Crane-Ultrasonic-Humidifier-Gallon-output/dp/B005PK7RW4 with a tube going to the top of the cage- that came on with my lights - I used a plastic tube about the same width as the hole at the top and worried more about being able to take it all apart for cleaning than if all the steam went exactly where I was pointing it. If you use one like it you want a "cool mist" - and they need to be cleaned regularly -