Do you have any other usb devices? If not see (1)
If you do see (2)
(1)In that case, you need to check the following, does your operating system support usb. You should be running Windows 98 or 98SE, Windows 2000 or ME.
If you are using one of these, are your usb ports correctly configured, check in device manager (right click on my computer and select properties, then device manager).
(2) Does your usb port produce sufficient power to run a scanner, it may be that you need a powered usb hub to provide enough power for the scanner.
Go to www.usb.org for in depth information into usb