We recently started using the EPDM software along with SolidWorks.  Having an issue with random drawing files in the vault not letting me check it out for revision work.  Just noticed this problem a couple days ago.  Prior to that, it wasn't an issue.  Now, certain files when right-clicked, the check-in & check-out options are not active.  Any suggestions as to why?  There is no pattern to the problem and nobody else has the files checked out.

Thanks!