It is driving me mad, every time i take my van into my garage the mechanic gets the fridge to run just fine, everytime i camp using the gas the fridge keeps going out

The appliances are all westy as are the fitments, the stove works fine!!
The gas is a large butane bottle running a 30mbar regulator, plenty of gas in it!
Does any one have any suggestions to resolve this issue. fridge works fine on 12v and mains
many thanks
Andy