I am will to bet that your scanner's imaging device is a CIS device.

A CIS imaging pick-up device equipped scanner is inferior to the alternative, a CCD imaging device, in that a CIS device cannot pick-up fluorescent colors and shades, and then, it gives those colors an off-white/creme, splotchy appearance.

Nearly all "all-in-one" devices (printer/scanner/copier) are CIS equipped machines, which is why they are cheaper than CCD equipped devices.

Jim