Hi Ian.
Silencer.....not a clue mate to be honest.......looks like an AA
Check the cylender seal AGAIN mate, and when you screw it back on the rifle dont overtighten it.
Also look to see if the cylender is being obstructed by the inside of the stock at all, preventing the cylender going all the way home.
If that does not work, empty the cylender completely using the tool provided.
Then fill, with bursts of air, empty again, and fill properly.
Could be a bit of muck in the filling valve.
Bill.