In the past, I've only used bottles. For my last batch I tried a 5l mini keg. I put priming sugar and beer in the keg and capped it off with a rubber bung with a screw in it. Yesterday, after plenty of time for carbonation (>8 weeks), I tried to drink the beer, but it was flat. The taste was fine but there was no carbonation. It seems to me that pressure was released through the screw in the bung. Any advice on how this process it supposed to work, or what I'm supposed to do with the screw in the rubber bung? There seems to be a good seal around the edges of the bung because it is fairly difficult to push on. Also, I have another mini keg full of beer and I'm not sure if it's flat. How can I check if it's flat, and if it is, can I recarbonate it?