RHP help!!!

[Newtot]

Yall i am so confused!!!!! I have a diy enclosure for my boa. I got the rhp from pro products, they said it would work fine with my thermostat. Anyhow. I had the probe set mid way down the wall under the panel. Set it to 90, the thermostat stays on constantly and is only getting to 85. What im i doing wrong? The thermostat works because i used it on her other cage for a heat mat. Im thinking i may need to switch it out for the exo terra pulse proportional one i have instead.