samba - Oct 2009 - How do I get Samba to probe for my ldap module ?

I'm compiling Samba 3.4.1 with

./configure --with-pam --with-ldap --with-shared-modules=idmap_ldap

This produces an ldap.so module which I have copied into /lib (and run
ldconfig -v).

However, following this log.winbind-idmap is not created (only log.smbd
and log.winbindd) and Samba does not appear to probe for the ldap module
(I have compared my case to another which is creating this log file and
also probing for the module, see
https://bugs.launchpad.net/ubuntu/+source/samba/+bug/397203)

What am I missing ?  I've tried to give Samba a hint that I want to use
idmap_ldap, i.e.

idmap alloc backend = ldap
idmap uid = 10000-29000
idmap gid = 10000-29000
winbind enum users = yes
winbind enum groups = yes
idmap alloc config:range = 100000-500000
idmap alloc config:ldap_user_dn = cn=admin,dc=seat,dc=massey,dc=ac,dc=nz
idmap alloc config:ldap_base_dn = ou=idmap,dc=seat,dc=massey,dc=ac,dc=nz
idmap alloc config:ldap_url = ldap://127.0.0.1/
idmap config SANDBOX : backend = ldap
idmap config SANDBOX : range = 50000-59999
idmap config SANDBOX : ldap_url = ldap://127.0.0.1/
idmap config SANDBOX : ldap_base_dn = ou=idmap,dc=seat,dc=massey,dc=ac,dc=nz
idmap config SANDBOX : ldap_user_dn = cn=admin,dc=seat,dc=massey,dc=ac,dc=nz
idmap config SANDBOX : ldap_alloc_url = ldap://127.0.0.1/
idmap config SANDBOX : ldap_alloc_base_dn ou=idmap,dc=seat,dc=massey,dc=ac,dc=nz

Regards,

Patrick