Excel File Opening Problem on Multiple PCs

Hi,

I have an 8TB My Cloud Home device. The device itself is working fine. However, I have placed an excel file in a folder. When two users from 2 different PCs open the file, it opens on both PCs in editing mode without prompting any single user that “The document is locked for editing by another user”. This is abnormal behavior. As one of the user will loose its data whenever 2nd user saves the file. Has someone else encountered this problem? A help will be beneficial. I just need that if excel file is open on one PC, all other PCs should see the prompt “The document is locked for editing by another user”. So that they can not edit this file. Thanks.