You need to be able to shine light through film to scan it. If you have a scanner that only reflects light off the film (i.e. a normal flatbed scanner without a transparency adapter), then you can't scan film with it.
If your flatbed scanner has a lamp in the scanner lid, make sure you've plugged the cable from the scanner lid into the back of the scanner.
If you're using a Canon scanner on 64-bit Windows, make sure you're using the x64 version of VueScan 9.
Check to see that the "Input | Mode" option has a transparency option.
You can always sell it again on eBay when you're done with it. You might even sell the Nikon scanner for more than you paid for it - prices have been going up since Nikon stopped manufacturing film scanners.