You say you replaced the small regulator. Did you replace it with a RED high pressure regulator?
Are you sure you have propane in the tank? It wouldn't be the first time someone swiped a full tank and replaced it with their own empty tank.
Bob and Joyce
2013 CC Silverback 29RL
2010 Ford F250 XL Crew Cab 6.4 liter diesel
ATU Local 788
I had the same problem a couple of years ago. I don't know all the technical jargon, but there is a safety valve inside the hoses that is volume specific, basically if the flow is to great the setup is designed that it recognizes this as a leak and the valve closes. I replaced mine with a new hose and had the same problem as I got the incorrect volume of hose. Try switching the hoses off the regulator and see if the problem follows.