Removed the original thermostat and replaced with a honeywell RTH6350 thermostat. Labeled all the wires and put them back into the correct place on the new thermostat. When I removed the old one, there was a purple wire not connected and the end covered in tape. Once I installed the new thermostat, I get A/C but now I am not getting heat. It is electric A/C and Gas heat. I do have a full tank of Gas and the valve at the unit is on. Any suggestions on why I can not get any heat from this unit?