Some Questions..

[Craiga 01453]

The probe should be between the heat mat and glass. Putting the probe under the substrate is pointless, and can also give incorrect readings which leads to heat spikes which leads to burns and other issues. Also, speaking of substrate, what IS your substrate?... it looks like gravel or something...
Sorry if this was already mentioned.

I agree 100%. The probe goes OUTSIDE the enclosure. If it's inside it can be moved, peed on, laid on, etc...which can all cause potentially dangerous heat spikes.

you can still have your probe on the inside of the enclosure(which is what I do). That way you get a reading of what temperature your snake is getting. At the same time just set your controller a degree or two higher because it has to warm up past the glass and substrate. Just make sure you use the thermometer to read inside and you’re fine. Outing the probe between the heat mat and glass, or on the inside of the enclosure really doesn’t matter, because at the end of the day you can change the set temperature on the controller to get the desired temperature within the enclosure.

I disagree, for all the reasons above.