How to get rw on files on unix from nt

[shapi003 at mc.duke.edu]

I have a user called puffin on unix that I put in a group called stuff
There is a user called stuff too.
I create as stuff a file in the stuff directory called INDEX.
I have a directory owned by stuff, but I do the following:

chgrp stuff
chmod -R 575 stuff (this changes INDEX to have 575 too)           rx rwx rx

puffin can create a file in the stuff directory and read stuff, but he can't
change and save stuff in the INDEX file.  I tried to use NT to remove the read
only, but that doe not work.  As a member of the group stuff, I was expecting
puffin to have read/write ability.  What am I doing wrong?

The smb.conf has the following:

[stuff]
   comment = Web pages for NSST
   path = /stuff/
   valid users = @stuff
   public = no
   writable = yes
   read only = no
   write list = @stuff
   force group = @stuff
   printable = no
   create mask = 0777

A lot of the options were put in as an attempt to fix this.

Your help is appreciated in advance.

Thanks,

David