wait, I'm sorry I'm confused. Where outside is it suppose to be? I have the heat pad on the under outside portion of the cage. NOT inside the tank, so your saying the probe is suppose to be under outside the the tank? sorry, just seems a little off. the probe is suppose to measure the temp INSIDE the tank isn't it, It's inside the cave and shows how hot it is inside the cave. if I set it at 98(the thermostat) it measures and goes off that, then puts more or less heat on the heatpad then rises up inside the cave. right? main purpose of the probe...if its outside its measuring outside temps not inside.