--with-ldap prerequisites

Hi,

I am trying to compile 8.2.4 on solaris 10.

I would like to use ldap authentication so I specified --with-ldap however I get the following error.

Undefined                       first referenced
 symbol                             in file
ldap_start_tls_s                    libpq/SUBSYS.o


I assume this is because I haven't installed the openldap libraries?

Is there any way to use ldap authentication without installing open ldap?

Could I use the SUNWlldap package?

I want to eventually authenticate against an active directory domain.

Thanks,
Simon