CA LDAP cant connect using the port and IP address specified because of a TCPIP issue.
Please make sure port 389 is not being used by another application. The port being used cannot be shared by CA LDAP. It must exclusively use it. Please contact your network person who configures TCPIP on your mainframe to see if the port is being used and what ports are free. Any port number can be used, it just has to be unused.
Can you ping the IP address and see if you get a response? If not, you need to contact your network administrator to determine why?