I had this problem but in reverse I couldn't get it off.
Just a thought it might be your problem. How much of the button on end is sticking out of the handle if only half inch then the handle rubber has worked it's way up so obstructiing the button and this may be holding the ratchet pawl off the cam teeth. Give it a try. IF not that get hold of Lunar
Lunar Caravans (Leyland) Ltd
6 Sherdley Road
Lostock Hall
Preston Lancs PR5 5JF Tel: 01772 37628
Lunar Caravan Specs
Bob
April 2009