When uploading a new file to your Filemaker Pro server (in this case FMP 13 Server) It's always good to remember to go into edit Privilege Set and add the Extended Privileges:

"Access via FileMaker Network (fmapp)"
AND
"Access via FileMaker WebDirect (fmwebdirect)"

That way you won't spend half the day (or so) scratching your head when you get this error message:

       The file "My_Cool_Database.fmp12" could not be opened. (Not Found)