samba - Aug 2002 - samba user add command requires NT administrative priviledges

Hello,

I have installed Linux RH 7 in my test environment. And i am facing some
problem in the task.

I have NT 4 server as a PDC, and RH server using samba. I am able to share
the folders in this test domain.
I am trying to use add user command of samba and upto some extents able to
use that.

When there is no unix account present-

Problem here is, when I login on a NT/2000 workstation as a member of admin
group, i am allowed to access shared folders on samba server
and adduser commands succeeds and creates new user account on Linux box.
(perfectly right)

but when i revoke admin priviledges from that user (NT) , i cannot access
same shares on samba server, but it asks for username/password.
Also it doesn't create that new user on the Linux box. ( something wrong?)

Can you help me to find this out?

Regards, 
Aashish