My neighbors have an outbuilding which is primarily heated with a vented wall heater running on propane. Its the kind that you might find in an engineer's field office trailer.. actually, I think thats where it came from. Every summer they shut the flow off at the heater and tanks, and every fall, turn it back on again and try to re-light the pilot light. However, every fall it seems that there is no flow of gas coming back through the line. They usually call the heating guy, but I'm trying to get it figured out first. I've checked all of the connections. All of the valves are on and gas should be flowing. Is there anything else I should check?