It's a plastic container which I thought would hold in the heat/moisture better. It measures 22 long x 16 wide x 11 deep. I've tried everything from 100% open to 95% covered. No effect.

I'm not using a ceramic heater or a heat lamp. I'm totally confounded.

I tested my thermometer/humidity sensor and it's reading correctly. My humidity has actually gone down following all this. It went from 47% two days ago to 28% today!

Help me!