I'm just getting back into making beer after a lengthy break. I'm suddenly faced with what is a daft problem. I've used my old Hambleton Bard barrel and replaced the cap, which looked a bit dodgy, with a new one complete with new brass valves. The input valve has a concave base inside with a little hole - there's no spike. I needed to top up the gas but when I screwed a new cylinder of gas onto it - nothing! Have I got the wrong equipment or possibly a non-working cylinder? Apologies if this is a bit pathetic but I can't see what I'm doing wrong.