Connect USB drive to Airport Extreme

[rjvideoguy]

I recently purchased an airport extreme router and am trying to add an external hard drive to the usb port. I have done the following:

1. Connect the hard drive to the AirPort Extreme USB port.
2. Open AirPort Utility, select your base station, and click Manual Setup.
3. Choose Disks in the toolbar and enable file sharing in the File Sharing tab.

I am unable to discover this drive on any of my PC's. Help