samba - Nov 2009 - smb w/ldap get joined to nt4 but net rpc vampire fails with NT_STATUS_ACCESS_DENIED

I am trying to migrate our Windows NT 4 Domain to Samba 3.4.3 and got
the error message below when I run the command:

"net join -S myPDC -I 172.30.1.1 -U administrator%mypasswd"
worked ok

"net rpc vampire -S myPDC -U administrator%mypasswd"

Fetching DOMAIN database Failed to fetch domain database:
NT_STATUS_ACCESS_DENIED

What I want to accomplish is to remove Windows NT 4.0 server as PDC and
make Samba our Primary Domain Controller.  Looking at Chapter 9
"Migrating NT 4 Domain to Samba 3" on Samba-3 By Example book that it
is
possible to merge or migrate NT domain to Samba using ldap & smbldap-tools

Can someone please point me to the right direction.
Thanks