Can I confirm that your system configuration consists of a laptop with a local C: drive, connected to a network where there is a 1Tb network drive which has a USB port to which another 1Tb USB device is connected?
Can I also confirm that your intention is to create an exact copy of the network 1Tb device to the USB 1Tb device ??
Are the drives visible in explorer with actual drive letters mapped ? Unless drive letters are allocated to these drives, I don't believe Ghost will be able to pick them up.