Hi Guys,
You may faced many issues with Webmin and OpenLDAP LDIF-format configuration and it's something hard to fix. But don't worry, this bug is fixed in all new version of Webmin ( 1.470 ) and OpenLDAP LDIF-format configuration file support is added. If you are having an older version, then upgrade to 1.4.70. After that you can proceed with OpenLDAP configuration without an issue.