A file must be affiliated with the correct volume to be recovered successfully. As mentioned above, File Scavenger® should perform this association for you in all but the most severe cases of disk corruption.
Unknown Volume
Sometimes File Scavenger® cannot determine unambiguously which volume a file belongs to, such as when overlapping defunct volumes are detected. In some other cases, a file may not belong to any detected volume, such as when the volume the file belonged to has been overwritten completely and could not be detected. In both cases, the file is displayed under Unknown Volume, and the Volume column is left blank.