Furnace problems

Hi all--
I'm presently camping in AZ. The furnace is not putting out heat. Not sure what I am doning wrong. Both propane bottles are on. Propane is flowing fine all three burners of the stove. Water heater is working off the propane and water is hot.
When I push the thermostat up the heater clicks on and I can see what appears to be a pilot light on behind the furnace vent in the trailer. It should click and the burner should light but the burner does not light. So I get essentially cold air forced through the vent, warmed only a tad by the pilot light.
Maybe I'm missing something because I have not used the furnace in a while, but, heck, it was chilly last night!