Hi guys, as the title says: I can't get hot enough with a hydrofarm thermostat.

I thought I'd just describe my set up and see if anyone would have any advice.
First off, this is a trial/mock set up, there are no animals in here. I'll try to be as specific as possible; I've got a 40 gallon glass terrarium with a mesh top with the majority of it covered by a piece plexiglass, I have a Zoo Med reptitherm U.T.H. that I've used aluminum foil/foil tape on the bottom of it to stick to the tank; and I have it hooked up to a hydrofarm thermostat with the probe taped directly onto the U.T.H. with aluminum foil tape. I have an Acurite digital thermometer. The tank is held up on the rubber feet that came with the U.T.H.. There are no box fans or window AC units, the room is cooled by central air to around 73-75 degrees. Unregulated, I have gotten temperatures from the high 90s up to 110 degrees(or greater) directly on the glass above the U.T.H.; with the Hydrofarm set to it's highest temperature(108 degrees) I get 85-86 on the glass, and that is checked with 2 different Acurite probes. On substrate(3-4 sheets of newspaper) the temperatures above the heat pad drop even further to 82-83. I think those are all the applicable details.

Now I'm wondering if anyone can help me troubleshoot this, It seems like I can only get it too hot or too cold. I'm thinking maybe it's the glass tank itself just isn't keeping the heat well; I really have no reason to think the thermostat or the U.T.H. are defective. Now I did use aluminum foil on the U.T.H. so I can move it around. I would like to find a solution for the glass tank, but I also have a 34 quart sterilite tub that I can set up and compare results. So, hopefully someone who has done this a few times has some ideas, suggestions, or advice on creating a suitable ball python environment; I'd be very grateful to hear them.

Thanks