It would help if you included the UPC so that someone can attempt to add it to their collection to see if they get the same error .

I own the same UPC as TheDarkKnight (027616085535). If this is the UPC you are trying to add, you might have a problem with your local database.

Or these files could be corrupt:
OnlineList.dod
OnlineListSel.dod

Close DVD Profiler. Then rename these files to .old. Restart DVD Profiler and goto Online --> refresh online profile list. Then try to add the DVD again to see if that fixes your problem.