samba - Feb 2010 - Bug? Problem with domain joining: invalid dn (sambaDomainName=fnf-int, (null))

hello list,

I habe to upgrade a SAMBA/LDAP installation from Ubuntu 8.04 to Ubuntu 
10.4 (alpha2) because Windows 7 needs to be supported.

I started by upgrading the BDC (OpenLDAP configured as consumer) to the 
new version, making sure that XP can join the domain and users can log in. 
As this was finished, I upgraded the PDC (holding smbldap-tools and 
OpenLDAP configured as producer).

Both installations I did as clean install (not by issuing apt-get 
dist-upgrade or the like).

I have transferred the SAMBA, LDAP and smbldap-tools configuration from 
the old distribution to the new one and think that it should be okay. 
However, when trying to let an XP host join the domain I get the error


slapd[4734]: conn=8 op=2 do_search: invalid dn 
(sambaDomainName=fnf-int,(null))


XP says: ?The following error occurred attempting to join the domain 
"fnf-int": The specified domain either does not exist or could not be 
contacted?.

This looks as if the LDAP suffix in either smb.conf or smbldap.conf is 
missing but this is unlikely because I have copied them from the old 
configuration. I also checked and they're there.

I already tried changing the entries in smbldap.conf from 
usersdn="ou=Users,${suffix}" to
usersdn="ou=Users,dc=fnf-int,dc=intern"
(so expanding the suffix variable), but this did not change the behaviour.

Is this a bug?

Can anyone help?

Best regards

Sven Ehret