thermostat issue

[poscash3757]

I installed a thermostat for my gas fireplace. It has been working fine for about 3-4 weeks. Recently it will not start the fireplace from an idle start. It will only shut off/ turn on when the t-stat is at temperature. When we are not in the room the t-stat is on off. When we are using the room the t-stat turns to the auto position when we turn on the room. I need to go flip the fireplace switch first then the t-stat will work correctly after the initial start up. Anyone have any suggestions? I have an external power supply hooked up. The wires are going to the r terminal and I believe the common. The fireplace wires are connected to the red terminal and one of the white terminal. Pic attached. I am running about 30 feet of cat 5 to the fireplace.

Thanks

Matt