I have read the diy c02 and followed exact instructions on making one but for some reason mine never works. here is my process... i use a 2 litre bottle with a hole drilled on top with a airline through. i then take 1/2 tsp(2.5ml) of active dry yeast and then mix it with warm water 1/4 full in the bottle and mix really well. then i add about 2 cups sugar and again mix. the other end of the airline is then stuk in the tank but nothing ever bubbles. is this the process of how its done. i've been doing this and it doesnt work? Can anyone Help???