A:Answer Are you using the USB plug that came with the headphones, Bluetooth, or another Logitech USB plug that came with a keyboard or mouse? If you are using a plug that came with a keyboard or mouse, you will have to use the headset USB plug in addition to the keyboard or mouse one.
The advertising is misleading, but headphones cannot be one of the several devices that can share the a USB plug with other Logitech items. Hope this helps, I had the same issue and it took me about an hour to figure it out.