Oh I had to do a little of reopening the client and make it first run at 1,6 then I am able to overclock it to 2,2.
But there is one that do not want to work at 2,2 but at 2,1 yes.

Might it be my usb port that doesn't receive enough power ?
Because I have 3 block erupters and 2 antminers directly plug in my computer usb ports...

Thx Doc !!!