What have you been using? If it's one of those inexpensive round stick-on things they always carry in pet stores, they're not accurate, plus they come "un-stuck"
and then can get horribly re-stuck on the snake, sometimes causing injury when ppl try to remove them. Keep all tapes & such sticky things out of snake cages...when
a snake gets under/over the heat, those things become "hot-glued" onto their skin. If that's what you've got right now, pull it out & cover any remaining sticky area with
something so the snake cannot contact it. It's not working anyway...and if you've got condensation, open up the cage for a while to help clear it out. You'll get this fixed
soon enough with a good gauge.