modifying ldap configuration

[Asmaa Ahmed]

Hello,
I am trying to get ldap works with kerberos by enabling sasl kerberos authentication to access LDAProot at auth-dev:/home/aahmed/ldapConfig# cat /etc/ldap/sasl2/slapd.confpwcheck_method: saslauthdmech_list: GSSAPI
Now I am trying to modify cn=configroot at auth-dev:/home/aahmed/ldapConfig# ldapmodify -Y EXTERNAL -H ldapi:/// -f olcDbIndex.ldifSASL/EXTERNAL authentication startedldap_sasl_interactive_bind_s: Authentication method not supported (7)	additional info: SASL(-4): no mechanism available:
Is there something missing here? or I am using the wrong options?
Thanks.