ldap_modify_s Insufficient access

Users in my LDAP database have trouble changing passwords.

$ passwd Changing password for user XXX. Enter login(LDAP) password: New password: Retype new password: LDAP password information update failed: Insufficient access passwd: Authentication token manipulation error

In /var/log/message, I have: passwd: pam_ldap: ldap_modify_s Insufficient access

In slapd.conf on the server, I have the following:

database bdb suffix dc=mydomain,dc=fr checkpoint 1024 15 rootdn cn=Manager,dc=mydomain,dc=fr rootpw {SSHA}XXXXX

access to attrs=userPassword by self write by * none

access to dn.subtree="dc=mydomain,dc=fr" by dn="cn=Manager,dc=mydomain,dc=fr" write by self write by * read

Any idea what is wrong? Thanks in advance.

F.