Cannot get propane to flow

My regulator does not appear to have a green flag in window, just a red one that disappears when I open the valve on either cylinder, so I don't think the pigtails are bad. Like I said earlier we have camped at KOA 4 times and all the appliances work fine. Its just when we are at the storage place with no hookups we can't get propane to work. The guy from the dealership thought the hot Texas air may be heating up the air in the propane line and putting too much back pressure for the propane to flow. And when we drive the trailer for an hour to the KOA the propane pipe cools down so maybe that is why it seems to work there. Problem is wife wants me to get refrigerator cooled down before we leave site.