Being a 2012 Scamp
you should have a newer tank with a safety shut off valve which is intended to shut off gas flow if a line gets severed. The tanks with the valve have a roughly triangular shaped valve handle.
Did you disconnect the tank for some reason before you had the problem. If so you may have opened the valve too quickly and tripped the safety valve. I have had this problem in the past when I was in a hurry.
Here is the sequence to solve the problem:
-Turn off the valve at the tank.
-Loosen the connection from the tank to the regulator. You should hear a short hiss as the pressure releases at the connection.
-Now crack the valve open slowly to establish back pressure on the safety valve.
-Now open the valve all the way.
If this solves the problem, you have just confirmed that the safety valve is working. That's a good thing.
Hope this helps.