Why can't I set organization?

[Emre Sevinc <emres@bilgi.edu.tr>]

I can't set my "organization" as you can see
from the headers of the message. I've read FAQ
and created such a ~/.gnus file:

===============================================
(gnus-compile)

(setq gnus-posting-styles
  '((".*"
      (name "Emre Sevinc")
      (address "emres@bilgi.edu.tr")
      (organization "Istanbul Bilgi University")
      (signature-file "~/.signature"))))
===============================================

However when I'm composing a new message the headers
of the message template is created as:

===================================================
Newsgroups: gnu.emacs.gnus
Subject: Why can't I set organization?
X-Draft-From: ("gnu.emacs.gnus" "")
From: Emre Sevinc <emres@bilgi.edu.tr>
====================================================

No reference to organization field as you can observe.
What am I doing wrong? How can I set my organization?

Any clues?

Thanks in advance.

-- 
Emre Sevinc

eMBA Software Developer         Actively engaged in:
http:www.bilgi.edu.tr           http://ileriseviye.org
http://www.bilgi.edu.tr         http://fazlamesai.net
Cognitive Science Student       http://cazci.com
http://www.cogsci.boun.edu.tr