I would suspect that you would need to draw power off of that port for the port to accept data signal. Even externally powered USB devices draw a small amount of power off of the ports.
"Far better it is to dare mighty things than to take rank with those poor timid spirits who know neither victory nor defeat." - Theodore Roosevelt

-USMC Corporal Hess Sherrod B:6/6/84 D:4/6/09 I miss you, my brother.