TuneUp Shredder doesn’t seem to work

You are probably trying to shred a file that you have previously restored with TuneUp Undelete. Unfortunately, this is not possible because TuneUp Undelete creates a new file with the contents of the deleted file during the restore process. This means that you are only deleting a copy of the deleted file and not the original file.

An complete explanation and more information about how TuneUp Undelete and TuneUp Shredder work can be found in this support article.