Not getting gas?

Dumb question, but are you getting gas to any of the other appliances? If not, and you open the line from the regulator to the trailer and then open the valve on the cylinder momentarily, do you hear gas flowing?  

Looks like my problem is a defective gas gauge on tank.

When I took off the gage, gas began to flow.

Okay. I understand what is happening. I have one of those gauges and it also malfunctioned. It let gas through, but as soon as an appliance started using gas, it could not keep the flow up and the flame dropped. I could see the needle going down. I took a pipe cleaner (they are still around, but mostly for crafts now) and poked it through the hole in the end that has the acorn nut. There must have been something in there since It started working properly after I did that. I would not guarantee that the same procedure would work for you, but it would be worth a shot if you wanted to try to save that gauge. The better bet would probably be to replace it though. Or, just use the hot water method to check the level in your tank. It is much more accurate than the gauges and does not cost more than a little time to heat some water to pour over the tank.