First, an apology to Jennifer. Upon examining the photograph more closely (wish she would let you all see it) I see that I AM mistaken about it being sand in the bottom of the cage. I'm terribly sorry, Jennifer, for saying you used Sand.
Jennifer, in the interest of success, because you won't let everyone see the picture (to see that the thermostat probe is two inches under the lid of the 10-gallon tank, on the back glass) I'll tell you (again) that the probe and/or thermometer must be where the snake is. You have it in your mind that a 10-gallon tank is the same temperature everywhere therein. You now see how wrong you have been all these weeks, by setting the thermostat for low 80sF but achieving 70F on the cage floor (which is also on the floor of the room--the coldest place in any home). As I said to you many times, there is only one place in the cage where temperature matters, and place is where the snake spends most of its captive life IN the cage. Had you shown the picture to everyone, the first advice you would have received was that you don't control the temperature on your front porch if you are living IN the house. That analogy is parallel to putting the thermostat at the ceiling of the cage when the snake is on the floor of the cage.
Not the entire picture, here is a portion of the cage pic that shows the cage mat that I incorrectly perceived as sand. I'm very sorry for incorrectly saying it was sand, Jennifer.