The "security mask" parameter

[Mohammed_Maati at BIOGEN.COM]

I am a new Samba user so forgive my ignorance.
I am using Samba version 2.0.6 on HP UX 11 and I need to use the "security mask" parameter to prevent even the owner of a file from changing the read
only attribute
(by right clicking on the file from a  Windows NT 4.0 desktop) if the file is read only (Unix permissions: 0440). This is what I have in the
"smb.conf" file:
[global]
nt acl support = no
...
 [share]
...
 security mask = 0000
 create mask = 0640
 force create mode = 0000
...
But it doesn't do what I want it to do and which is what it's supposed to do according to the documentation.
Is there anybody that have an idea how to this work? Please help.
Please send me an email.
Thanks.

Mohammed Maati.