Replication/ Clients update slave

[Thorsten Mauch <mauch@imkenberg.de>]

Hi 
I have a a simple master - slave relationshop between 2 server
the master slapd.conf contain:

replica host=ldapslave.muehlhan.com tls=yes
binddn="cn=admin,dc=muehlhan,dc=com" bindmethod=simple credentials=secret

and the slave:
updatedn   "cn=admin,dc=muehlhan,dc=com"
updateref  "ldaps://ldap.muehlhan.com"

the replication from the master to the slave work perfect. 
My problem is that the clients can update the slave server directly, instead
of beeing
forwarded to the master server. 
Does there is anything in the configuration missing to enforce the
forwarding to the 
master server ?
I realy read the admin guide more then once but I don't know where is my
error.
Is there anyting in the config missing ?

Thx
Thorsten