exactly how do you have your tank set up?
i have a 70 glass tank the top is all sealed up with plexiglass with just a hole for my heat lamp (that i only turn on when i get the humidity too high) and cypress coconut bark mix for the substrate with flexwatt belly heat and the exception of the lowest temp in my tank being 75 and my hottest spot being 95 (but between there i have every temp between) its pretty much dead on