If you have other tanks (evod, protank II mini, etc) they will also fit.
I suspect you are just not making contact somehow. Wipe the inside and bottom of the magnetic connector, the 510 connection on the tankbefore you screw it on the connector, and the connection down in that well. Make sure the coil is screwed in good. Try another coil.
If you have another device, you can test the GS Air 2 tank without the magnetic piece. (As long as the other device will go low enough. The istick basic ships with .75 ohm coils I believe)