Ambient temperature higher than surface temp??!

[Keshi]

Hi,
If you use light bulb for heating, the ambient temp can be upper than the surface temp. I don't know what you use to measure it, but maybe the problem is here. The aquarium is screen top?

thanks for getting back to me so quickly. No it's a wooden top with glass doors. I've got a dial gauge at the mouth of her hide and a dial temperature and humidity gauge on the back wall. The thermostat probe is at the back of her hide.