are you sure you installed the correct drivers?
there are often drivers for many of the company's products on the CD they give you, and Windows doesnt often seem to understand which is which.

did you install everything that is required?
for my digital camera (admittedly a cheap & nasty one) I had to install the TWAIN driver first, re-boot, then install the hardware driver, then re-boot.

I would recommend going thru the install process again, and making sure that you carefully follow all steps that are specified in the manual.