1) The on/off switch on the fireplace and/or wall may be in the on position. This will over ride the remote control feature.
2) The remote is in the thermostat mode (SMART-STAT and RCT-MLT models) and the temperature of the room has not exceeded the desired temperature setting by 2 degrees Fahrenheit or 1 degree Celsius.
3) Batteries in the hand-held transmitter are old and underpowered. May work up close and will not work a few feet away.
4) Hand-held transmitter is outside of the 25’ of operation.
5) Hand-held transmitter has been dropped and the frequency has been moved off the frequency of the receiver.