The latest version of OpenLDAP in Debian GNU/Linux ,slapd 2.4.11-1, don't allow a empty sn. So, if we try add a contact whitout lastname, an error is provoke on OpenLDAP server.
Another question is that the cn object is make with first name and last name. I now check if exists last name.
Patch is added on attachment file.
Thanks.
Patch to solve the problem