You will have to first determine if the negatives are in proper density. I think you mean you have an F100? Regardless, unless you were using the spot metering mode and you had an 18% gray card to meter, camera's metering system can easily be fooled. If you shot in broad daylight, and you happened to have metered against darker than 18% spot, but rest of the are were less, it can easily be over-exposed - which will result in very dark negative. (or do you mean scanned and reversed images are too dark?)
Without knowing what your negatives look like, trying to figure out if the problem was the scanner would be impossible.... On top of it, you say quality of the negative itself is somewhat doubtful....
I'd say you got way too many variables there....