Calor Gas Bottle Fitting

Hi
I'm in Portrush area heading around by Causeway Coast. My 6kg Calor Propane bottle has run out. I was carrying an 11kg as a spare and I only realised when I went to change over that the 11kg has a different fitting. The 6kg has a female fitting whereas the 11kg has a male fitting.
I got a new 6kg bottle in Portrush here and even though the fitting screws in ok,no matter how tight I screw it,it leaks at the connection. I tried a 2nd bottle at the shop with the same result.
Would there be a difference in the southern bottle and the northern bottle,even though the fitting seems to screw in properly.
Or is there somewhere I could get a fitting for the 11 kg bottle today along the north coast
Thanks
Paddy

Hi, Paddy.
Did you check the rubber o ring at the conection hose where it screws onto the cylinder. They are prone to damage and are available from most gas stockists