Heat pad directly on shelf

[Vypyrz]

Hey sorry to bug so much but I'm still in need of help
i raised my temperatures on the hot side to be 92F and the cool side is still at 69.8F
i have no idea how to raise the temps on the cool side
it's been running for about an hour and still no change
I'm beginning to think the zoo med UTH heater won't work for plastic tubs
my humidity is now at 61 and I'm wondering if I should make more holes?
thank you for your help

A UTH is designed to heat the surface area directly above it. Your cool side temperature is going to be somewhere around the same as the ambient temperature of the room it's in. What kind of room do you have the tub in?