Maybe somebody is using a file on /myrep (or you or somebody else have a pwd of somewhere under /myrep).

Try fuser /myrep to see what processes are using the fs. If you don't have fuser try lsof.

With fuser you can supply the -k option to send a SIGKILL out to any processes using the mount (e.g. fuser -k /myrep) - be careful though - you could boot people off the system (yourself included) and cause file corruption if somebody is for example editing a file, leave child processes, not cleanup after itself, etc, etc, etc.

Once you get a "clean" output from fuser /myrep that nobody is using the mount, remount it rw.

Cheers
ZB