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.
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"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.