I made a 5 gallong batch of the Gnome autumn red birch beer awhile back for the kids and for some reason, I can't seem to get to carbonate. I've had 45 pounds on it at 35 degrees F for over 2 weeks and it's just not going anywhere. I have a full tank of CO2 and I even tested it so I know that not the problem and I know the corny is not leaking either as I tested that too. This is my first attempt at soda and I do live at 6600 feet. Could elevation be the issue?