samba - Mar 2004 - configure failed, with option --with-ads (samba 3.0.2a)

I'm configuring samba v3.0.2a on Solaris 8 machine.
# ./configure   (completed, to be sure default is ok)
then rm configure.log and configure.status, start again.
# ./configure  --with-ads    (failed)
....
checking for ldap_initialize... no
configure: WARNING: libldap is needed for LDAP support
checking for Active Directory and krb5 support... yes
configure: error: Active Directory Support requires LDAP support
....
but libldap is on this machine:
% uname -a
SunOS hostname 5.8 Generic_108528-17 sun4u sparc SUNW,Ultra-2
% pkginfo | grep -i ldap
system      SUNWlldap      LDAP Libraries
% ls -la /usr/lib/libldap*
lrwxrwxrwx   1 root     root          14 Mar 24  2003 /usr/lib/libldap.so ->
./libldap.so.4
-rwxr-xr-x   1 root     bin       225808 Jan  5  2000 /usr/lib/libldap.so.3
-rwxr-xr-x   1 root     bin       225712 Aug 30  2002 /usr/lib/libldap.so.4

The reason to use --with-ads, is that I want to join Samba server to 
Active Directory domain as a member server.  (security = ADS)
 
Does samba requires different libldap as SunOS's?
 
thanks,
 
Jeffrey