samba - Jun 2010 - How do I get a real username in samba pdc instead of , , , ?

Hi,

I've got a Samba PDC running, there is one weird problem though . On
all Windows machines it shows comma's like this: ,,,  instead of the
user name. I used the following commands to add users and groups:

# net groupmap add ntgroup="Domain Admins"  unixgroup=root rid=512
type=d
# net groupmap add ntgroup="Domain Users"   unixgroup=users rid=513
type=d
# net groupmap add ntgroup="Domain Guests"  unixgroup=nogroup rid=514
type=d

# adduser username
# smbpasswd -a username

Is there something I can do to fix this? Thanks in advance!