The 2.2 ohm coils should work on the iStick without an issue. I don't know why it wouldn't work unless the coil has shorted out or something. It's also very possible you got a bad batch of coils.
@Susan~S ?
On another note, have you ever tried coiling your own coils? With a tank like the Kanger Subtank Mini (for example) you can use the rba (rebuildable atomizer) and re coil and re wick very inexpensively. You can even make them higher ohm coils like the 2.2 you are now using. (higher ohm means less power, less juice used) I'm certain there are many tanks out there that would do this for you.
Do your coils resemble this one: