samba - Sep 2000 - domain is blank when user changes passwd with smbpassd

Can some-one please help?

When a user connects using smbclient -L localhost they get the following
which (correctly) shows the domain :
$ smbclient -L localhost
added interface ip=10.2.2.2 bcast=10.2.255.255 nmask=255.255.0.0
Password:
Domain=[LECAU] OS=[Unix] Server=[Samba 2.0.7]
.
.
.

but when they try to change their smb password it fails, indicating a bad
username/password (even though it is correct) but the log shows that no domain
was used  :

[2000/09/20 14:51:59, 3] smbd/reply.c:reply_sesssetup_and_X(805)
  Domain=[]  NativeOS=[Unix] NativeLanMan=[Samba]

For some reason the domain is not being determined when smbpasswd is used
and hence the passwd failing

Can any-one **please** help me with where to look?  The security = domain and
all shares
are accessable by the users.  It is only the passwd changing that is a problem.

Thanks in advance

Richard Brodie