I have just sampled my most recent beer after two weeks in the BV (pressure barrel) and its distinctly flat with zero head. I have added a shot of C02 but hasn't made it much better. I added priming sugar when transferred it from the FV to the BV but doent have seemed to have done much. Can anyone shed any light on the reason behind this and if there anything I can do to improve it or better to chuck batch and start again?