AFP, excel file locked/read-only.

I've got an excel file that is shared via AFP that several people connect to and edit. When anyone tries to open the file, it says it's locked by a user and opens as read-only. The thing is, the user that it says is editing the file is not even connected to the AFP server. I can restart AFP and be the first to connect to the file and it still says it's locked by that user. What in the world is going on? Seems whatever I do, I can't make the file available for editing.