Openldap meta instance search microsoft AD issue

Hi

My issue is 

I use ldap meta to connect to multi AD.

The user acount in AD is 
e.g.  CN=Jeffrey Lee,OU=Technology,OU=LonUsers,DC=63stmarys,DC=uk,DC=westpac,DC=com,DC=au


 it works OK if in slapd.conf
rwm-suffixmassage   "ou=63stmarys.uk.westpac.com.au,dc=wib,dc=westpac,dc=com,dc=au" "OU=LonUsers,dc=63stmarys,dc=uk,dc=westpac,dc=com,dc=au"

But NOT work 
rwm-suffixmassage   "ou=63stmarys.uk.westpac.com.au,dc=wib,dc=westpac,dc=com,dc=au" "dc=63stmarys,dc=uk,dc=westpac,dc=com,dc=au"

Looks like meta ldap cannot search from root of AD?   when I set search base dc=63stmarys,dc=uk,dc=westpac,dc=com,dc=au it failed  but it start to work  when I configure one level down like
OU=LonUsers,DC=63stmarys,DC=uk,DC=westpac,DC=com,DC=au

Any comments? or please let me know what is the best place to look for the answer.


Below is my slapd.conf
database        ldap
suffix          "ou=63stmarys.uk.westpac.com.au,dc=wib,dc=westpac,dc=com,dc=au"
uri             ldaps://xxxxxxxx

idassert-bind   bindmethod=simple
                binddn="xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
                credentials="xxxxxxxxxxxxxxxxx"
                mode=none
                flags=non-prescriptive
idassert-authzFrom      "dn.exact:cn=Manager,dc=wib,dc=westpac,dc=com,dc=au"

overlay rwm
rwm-suffixmassage   "ou=63stmarys.uk.westpac.com.au,dc=wib,dc=westpac,dc=com,dc=au" "OU=LonUsers,dc=63stmarys,dc=uk,dc=westpac,dc=com,dc=au"
rwm-map attribute uid userPrincipalName
rwm-map attribute * *

Regards

Jeffrey Lee