Heat Tape/Thermostat problem?

I have a herpstat (not the grounded one, plugged into a power strip) set to 95 and the heat tape doesnt seem warm enough. I have a probe thermometer inside the tub and it will not warm up to more than 74 on the hot side. The herpstat probe is between the tape and the tube. Then
I unplugged the tape from the herpstat and plugged it into the power strip and the tape is alot warmer and the tub temp is rising. I am so confused right now. Help

Not 100% sure what's going on, but I tape my probe directly to the heat tape. I've never had any issues with this method.