[Samba] Problems with tdbsam database

[Timothy Dutton]

Hi
I am trying to set up a PDC with a tdbsam backend.
I ran into problems and decided to try starting the smb user list afresh
deleting the contents of the private directory, adding the samba users and
converting the database using the command pdbedit -I smbpasswd -e tdbsam

I get the message for all but the client$ user: the name of my test machine
tdb_update_sam: Failing to store a SAM account for [username] without a
primary group RID.

Can anyone tell me what I have done wrong?

Thanks in advance

Tim