I need to hook my portable grill to my RV propane tank. My RV propane tank has a thread fitting sticking out that is the same round as a 5ib propane tank. However a propane tank has a round brass piece inside so a regular hose fits it. my fitting has a little plastic insert sticking out inside so if I try to use a regular propane hose it does not screw on correctly. I have pictures if that will help. Please help i am planning on going camping soon and I want to hook up my portable grill to my RV propane tank, thanks.