I got one of madvape's tanks the other day, but I'm not sure if it's working or not. It's not leaking out, but my carto seems to be getting dry, and I can't tell if the carto is drawing in any liquid or not. I've already punched another hole beside the one that's there, but I still can't tell if it's working. I've tried sucking as hard as I can on it to see if it I could get liquid to the top of the carto, but I just got lightheaded instead. Anyone have any advice?