Just bought the istick 50w, went to the eleaf web site to authenticate and it says the number i entered doesn't exist. Bought it from my local guy. Not sure if it's a fake or not. But i noticed from pictures that the metal contact where you screw the tank into is silver and round. The contact on mine is gold in color and octagon shaped..Could this be a counterfeit unit? I also noticed my ohms keep bouncing from.3 to .4 , I'm using a .3 is this normal?