If there is a clear plastic cover on the probe take it off --- basking bulbs are trial and error -- you need that probe to get a actual surface basking temp -- do not change the 100 watt bulb till you are getting a actual temp -- 12 inches is fine for height you do not want that bulb any closer than 6" -- please go over the UVB your using - detailsThere is nothing I won't do or buy to make sure I have an ideal environment for him. My kids and I are already in love with him.