We set up the thermostat on the new rack on Sunday. We didn't have thermometers in the tub but we thought we'd give the thermostat a chance to heat up. We put a thermometer on the cool side, the hot side and added a hygrometer to the top tub last night. At first, both thermometers were saying it was below 80 on each side of the tub. We checked the probe to the thermostat and found it wasn't positioned quite right. We re-taped it to the flexwatt and have been monitoring the temps since about noon. The temp on the hot side, with the thermostat set to 92, is 81.4. The ambient room temperature is about 79. Any idea why this won't heat up?