samba - Jan 2004 - NT user add

Hi,

Is there a way to add users (or groups) from the nt file permission window
to a samba shared directory directory? So far we managed to change the
file permissions throught the nt file permission window but only for
existing users. What we see in the permissions window is the owner, the
group and everyone. If we try to add a new user (the 4th) we get an
"access denied".
Samba is the PDC. Samba version 3.0.2.

Thanks for any ideas...