Has anybody succeeded in getting a scan (from 120 roll film) longer than about 6x9 cm on a Nikon 8000ED with Vuescan (or any other scanner software)?

Have I made a mistake in assuming I can scan the full aperture of the 120 roll film holder (again, the Nikon 8000ED) by setting the Vuescan crop dimensions to values greater than 9cm?

I set (or believe that I am) for an image area of (roughly) 56 mm by 177 mm (approx. the image area I want to capture), the Vuescan status line indicates these dimensions and then produces a scan of ~6x9 cm.

Have I run up against a hardware limitation here?

New scanner (used), new software, newbie (old brain).