Hi my girlfriend got me a 'SKYCIG' for christmas, and i got a sample pack containing 5 flavours, i have used it quite abit and now two of the flavours have stopped giving out vapour and one im not getting much vapour when i drag on it, does this mean they are empty and the third is becomming empty, also im looking at trying a few new flavours and filling them up myself with e-liquid, do i need new 'cartrages' or can i refill my empty ones, also ive seen theese different ends will they fit my sky cig and do they give better vapour output than the standard skycig ones? im abit confused with it all so any help would be greatly appreciated.... many thanks