Anyone else having problem with the vapor? Even though I have charged the battery and the cartridge is new, nothing happens or just a little bit vapor. Maybe I should clean it? How often do you need to clean it (of course it depends on how much you are smoking, but let´s say after how many cartridges) and what is the best way to clean it? I´m using a sedansa cigarette and have used four cartridges since I bought it. Thanks.