x-drive is the all-wheel-drive system. I believe you mean the iDrive knob controller.
It is possible the USB in the glove box is not for iPod. There was a prototype I drove which had USB in the glove box wall, but it was just going to be for updating the radio.
I would expect a USB connector, then a cable with USB at one end and the special iPod 30 pin connector on the other. I would expect that to plug either into the glove box or the console. Nothing happens with either connection? Even if you connect the iPod, shut off the car, and come back like a half hour later and start up the car?
Some pictures would help, especially of the radio, "iPod cable", and USB connections.