This warning has the following causes and solution:
If a user has a lock on a file then, just retry the command in a few minutes.
If the lock hasn’t been deleted from the \DATA\LOCKS folder, go there and delete the .LCK file, however, please make sure everyone is out of VSS before deleting .LCK files or you may affect another users process.
If this warning appears when you log in to VSS, check to see if a \DATA\LOCKS folder exists. If it doesn’t, create one and attempt to log in again.