Samba join Error

I cannot join slave.
I’ve 3 working slave. On working slave univention-s4search cn=ucs-sso dn:

# record 1
dn: CN=ucs-sso,CN=Users,DC=domain,DC=intranet

# Referral
ref: ldap://domain.intranet/CN=Configuration,DC=domain,DC=intranet

# Referral
ref: ldap://domain.intranet/DC=DomainDnsZones,DC=domain,DC=intranet

# Referral
ref: ldap://domain.intranet/DC=ForestDnsZones,DC=domain,DC=intranet

# returned 4 records
# 1 entries
# 3 referrals

On brocke slave univention-s4search cn=ucs-sso dn:

Failed to connect to ldap URL 'ldaps://ucs-slave3.domain.intranet' - LDAP client internal error: NT_STATUS_CONNECTION_REFUSED
Failed to connect to 'ldaps://ucs-slave3.domain.intranet' with backend 'ldaps': LDAP client internal error: NT_STATUS_CONNECTION_REFUSED
Failed to connect to ldaps://ucs-slave3.domain.intranet - LDAP client internal error: NT_STATUS_CONNECTION_REFUSED

Why?
How can I fix it?
Thank you
Regards