Well no problem with your coils. The iStick can fire down to 1 ohms.
Davey59 might have a solution. The center pin of the battery may not be making a connection with the atomizer of the clearomizer/tank. This usually occurs from over-tightening the tank onto the battery connector. Just make sure that if you use something conductive (metal) to pry up on the center pin that you do NOT hit the fire button while you are working on the battery. Or better yet, turn off the battery.
Center Pin Issue - Fixing a non firing eGo battery