samba - Feb 2007 - Unknown parameter encountered: "domain admin group"

Hi all,
I am new to samba

(1) I installed Samba version 3.0.23c on Debian, kernelversion 2.6
(2) I try to setup a PDC (primary domain controller) using samba
(3) added "domain admin group = root " to [global] section in smb.conf
file.
(4) testparm show --> Unknown parameter encountered: "domain admin
group"
(5) when trying to add Win xp client to the domain it shows the error
massage " The user name could not be found"
(root is in the smbpasswd list)

What can be the problem ? plse help me


-- 
Kusum

Mobile +94776565825