I'd have to say again you might have just got a bad tstat. I guess this is why people say get the whole setup done and checked out before animals go in it, I hope this is what you are doing now. As I suggested in the other thread, if the one you have now is on/off you might as well just toss a cheapo 500R tstat on there for the time being until you have the funds for a herpstat and return what you have now. If you have the probes set up properly and it isn't user error then unfortunetely that only leaves a defective unit...