First, check if USB memory or USB card reader can be detected correctly.
The USB host portion of ND2725 is designed for those device.
If it works well, then the USB host portion is OK.
Then the connection problem may comes from power distribution issue. Connect power adapter to both of device(ND2700 and wd passport). Then try again.
If possible, power up both device, then connect USB cable later.
Answer by david2009-03-09
I had tried all of the mentioned combinations prior to posting - in the EX1 camera test it negotiates via USB correctly - but fails to complete the copy - but not any of the drivesb tested