Hi, we're touring Italy in our 2012 Swift Bolero 724FB, which has the Alde heating system. Our gas is supplied by an underslung refillable LPG tank. The heating works fine on electric and for a couple of weeks also worked on gas. Now though, the 'gas out' message flashes on the control panel, even though our gauge tells us we have 3/4 of a tank left and our fridge and burners work fine. I've been through the Swift manual and have checked the manifold switches are on, the exhaust is clear and all fuses are good. Can anyone suggest anything else please?