Make sure that you have enabled SSL in Directory Server.
 To Add the Active Directory CA certificate to the Directory Server
Certificate Database
To Add the Active Directory CA certificate to the Directory Server
Certificate DatabaseRetrieve the Active Directory CA certificate using one of the following methods:
Stop Directory Server.
Import cacert.bin into the <DS-server-root>\slapd-hostname\alias folder on Windows and for Solaris and Linux import it into <DS-server-root>/slapd-hostname/alias directory.
On the machine where Directory Server is installed, import the Active Directory CA certificate as follows:
If the certificate was retrieved using certutil, type:
| <ISW_server_root>\shared\bin\certutil.exe -A -d . -P slapd-hostname- -n ad-ca-cert -t C,, -i \cacert.bin | 
If the certificate was retrieved using LDAP, type:
| <ISW_server_root>\shared\bin\certutil.exe -A -d . -P slapd-hostname- -n ad-ca-cert -t C,, -a -i \ad-cert.txt | 
ISW-server-root is the path where ISW-hostname directory is present
If the certificate was retrieved using the dsadm command (on Solaris), type:
| /opt/SUNWdsee/ds6/bin/dsadm add-cert -C <DS-server-root> /slapd-<hostname>/ ad-ca-cert cacert.bin | 
Where ad-ca-cert is the name of the certificate assigned after the import and cacert.bin is the certificate about to be imported
Start Directory Server.