Joe,
This usually means that the ODB_DAEMON process is not running on the
DB_DAEMON_HOST machine.
Check your .caddsrc/.caddsrc-local file for what DB_DAEMON_HOST is set
to, then run /usr/apl/cadds/scripts/db_daemon on it. You also may need
to check permissions, as the user that the ODB_DAEMON process is running
under needs to have write access to the _db file.
Best regards,
Andy Bruce
PTC Global Services
Manchester UK