Flex Watt doesn't seem to penetrate tub?

[hondo1967]

The tape lies on top of the melamine board (so under the tubs). I think I'm going to raise the temps in the room and add flex watt to the back wall of the rack and see if that doesn't help. Thanks!

I use the flexwatt for back heat it works great with the helix, i keep it set to 94 and it heats the tub to 89