Scan the film sound "ka!ka!ka!" from the top light box, and the light box stop at 1/4 position. As the result, the scanning picture over exposure. Leo

SOURCE: Negative Scanning Problem Using Epson Scan Software

Make sure the rectangular slots at either end of the film frame are not obstructed or covered in any way. When I attempted to scan color negatives I had the same darkness problem in the scanned image. When I cleared those rectangular slots, everything was fine. I hope this helps.

SOURCE: film scanner bothom light dont turn on when scanning

one of 2 things, either you are not telling the twain driver that your scanning film, or your bulb is probably dead.
did it use to work?

SOURCE: Epson V500 scanner will not scan film

You're problem is Vista, not the v500!

SOURCE: Scanning in Epson 4180 perfection - trying to scan

Make sure the white document matt has been removed from underneath the lid. Then make sure that the document type has been changed from reflective to Film etc. If film is greyed out then check the cable is connected properly from the lid to the base of the scanner.

SOURCE: Problem scanning film with EPSON V300

check if upper cover remove for film scanning, bulb must be visible upon scanning in negative or positive film.