Can't get enclosure warm enough

[Midwest]

A couple things......If you don't, you should have the UTH on the outside bottom of the tank and the thermostat probe should be between the UTH and the glass bottom. Then the best thing to do is to use a infrared thermometer gun and check the temp inside on the glass floor surface.
The UTH should have no problem getting the floor temp of the glass to 88-90. In my tank I have 2 UTH one keeps the floor at 89-90 with a hide over it and another on the opposite end keeps the floor temp at 80. I have a very small CHE which keeps the ambient temp at around 80. A UTH will do little to nothing for your ambient temps. Lastly what is the temp in the room that the tank is in? In. The summer I don't need the CHE but in the winter the room stays at 70 degrees so I bring it up a little. You might also want to find a way to check the thermometer you have is accurate as well as the thermostat. I have 2 identical thermostats one is off about 4-5 degrees the other is perfect. A 15.00 infrared thermometer gun can help you a bunch

[WhompingWillow]

What are your ambient room temperatures?

As vivi said, make sure the thermostat probe for the UTH is sandwiches between the heat mat and the bottom of the tank on the outside of your enclosure.

For the CHE, hopefully someone who uses those will chime in with probe placement suggestions.

Part of the issue may be that it sounds like you are actually measuring ambient air temps as opposed to surface temps. To measure surface temps you'll want to purchase a temp gun. You can get them for about $15 on Amazon and can probably find one at home improvement stores.

What kind of thermometer are you using to measure your air temps? Is it digital or the stick on kind you find at pet stores? The stick on kind are wildly inaccurate. You want a digital thermometer to measure air temps. A popular one are the Acurite kind, about $8-$10 at most Walmarts.