That is an issue with the scanner.
1. When you turn the machine on, with the document feeder do you see the lamp coming on?
2. Shut the machine off and disconnect the cables from the scanner and document feeder, reconnect them and turn it back on.
If that is not it, A service call is the best thing to do, it is a calabration error in the scanner.
At the adjustment of CCD output after power on, CCD does not make a correct output which it should when it receives a specified amount of light.
Refer to BSD 6.3.
Check the lamp, lens, mirror and the white correcting plate for abnormalities such as contamination and deterioration.Abnormality such as contamination or deterioration of the lamp, lens, mirror or the white correcting plate is found.