i have a thermo stat. its a rheostat.
Two entirely different things.

A thermostat has a probe that measures the temperature then adjusts the electrical output to the heating element accordingly.

A rheostat provides resistance on the electricity so that the output of your heating element is reduced, but not intelligently.

I have never had luck using a rheostat and honestly its not too helpful, if there is a hot day you will have a hot enclosure and if its a cold day you will have a cold enclosure.

I would suggest returning the rheostat and getting a real thermostat, even the zilla brand thermostat will be an upgrade.