Trouble securely binding to Active Directory or other LDAP

[rhm54]

This code works perfectly when executed with an authentication type of "ServerBind" however when I change that to "SecureSocketsLayer" or "Secure" it bombs out with the error

System.Runtime.INteropServices.COMException (0x8007203A) The server is not operational.

Any ideas what I am doing wrong?

        Dim dirRoot As DirectoryEntry = New DirectoryEntry("LDAP://myserver.mydomain.xxx")
        dirRoot.Username = "USERNAME"
        dirRoot.Password = "PASSWORD"
        dirRoot.AuthenticationType = AuthenticationTypes.ServerBind