If you are seeing the three wavy lines after setting the desired temperature and a reasonable amount of time has passed, but the heat has not risen, check the following things:
Ensure the thermostat is wired correctly. Incoming power should be connected to terminals 2 and 3 (LINE), the HOT line MUST be connected to terminal 2. If not, the thermostat WILL power on, but WILL NOT pass current to the thermostat. The white/clear copper conductors should be attached to terminals 1 and 4 (LOAD), they can be connected to either terminal (no polarity). And ensure the ground braid is attached to the incoming electrical ground.
Check resistance of the mat/cable by conducting tests 7.1 and 7.2 on page 21 of the Heatwave Manual. In the event that the system fails either or both of those tests, contact Heatizon Systems for further instructions. 1.888.239.1232.
NOTE: Whenever working on ANY wiring for the thermostat, please TURN OFF the breaker powering the thermostat and floor heating system.