Operating a fridge on gas and Safefill

When you say no steady flame, does the ignition actually light the flame? If you are just getting the spark it would suggest no gas is getting through to the burners. If it is lighting but immediately going out ( I assume you are holding temperature selector knob in whilst clicking the ignition?) it points to a thermo coupling issue or it could be the burners. I had to have the burners replaced on a Dometic fridge on one of my caravans. 

David

just to check the obvious...

does the heating, hot water and gas hob all work....IE the supply is getting through the regulator into the other devices?

if so, and the isolation valve is open, then there must be a fridge issue, provided we discount 'operator error'

A small point, when lighting the fridge on gas.  The gas air mixture is critical.  It is quite easy to have too much gas and not enough air.  I would advise, pressing the igniter first and then the gas valve.  This mean you will have spark as the gas builds up.  Of course a service and clean might help. 

Another thing I have learned is that my fridge doesn't like running on Gas if the caravan isn't absolutely level.  I am glad to say that it was level when a site I was on recently had power failure somewhere around midnight!  I thought it might just be my pitch so I switched over to gas in a very sleepy state with fingers crossed!  Mind you it hasn't been long since the service so I was fairly confidant!