Enabling Replication

Hi,
I am trying to configure the RHDS in 2 of our machines. So I did created the instances, suffix and sub suffixes ,replications and also the agreements on one of the node. Now while trying to enable the replication authentication on that Node only by using the ldapmodify command. To be precise the command is ldapmodify -H ldaps://pd.example.com:636 -D "cn=Directory Manager" -W -x . (pd.example.com is the node hostname and 636 is the ldaps port).
This command asks for a LDAP password and by providing it, throws an error.

[root@pd1 ~]# ldapmodify -H ldaps://pd.example.com:636 -D "cn=Directory Manager" -W -x
Enter LDAP Password:
ldap_sasl_bind(SIMPLE): Can't contact LDAP server (-1)

What could be the possible issue and can anybody help me on this?