Root problem for sorting the summary buffer

[Sébastien Vauban]

Hello,

I've always had a problem regarding the sorting of articles in
the newsgroups.

Look at this:

--8<---------------cut here---------------start------------->8---
Q                    1970-01-01 01:00  0.0k     Re: Using `eval-expression'
R.+ Lennart Borgman  2008-04-03 15:53  2.5k           \-> ...
R.  Thierry Volpiat  2008-04-03 15:58  3.6k           \-> ...
R.  Nikolaj Schumac  2008-04-03 20:45  2.2k           \-> ...
R.  weber            2008-04-03 23:11  1.9k                 \-> ...
R.  reader@newsguy.  2008-04-03 14:52  2.4k               \-> ...
--8<---------------cut here---------------end--------------->8---

The poster's mail is presented as the last one of the list, with
all the answers being then correctly sorted (in chronological
order, from top to bottom).

What I logically want is:

--8<---------------cut here---------------start------------->8---
R.  reader@newsguy.  2008-04-03 14:52  2.4k     Using `eval-expression'
R.+ Lennart Borgman  2008-04-03 15:53  2.5k           \-> ...
R.  Thierry Volpiat  2008-04-03 15:58  3.6k           \-> ...
R.  Nikolaj Schumac  2008-04-03 20:45  2.2k           \-> ...
R.  weber            2008-04-03 23:11  1.9k                 \-> ...
--8<---------------cut here---------------end--------------->8---

I thought I had correctly set up Gnus therefore:

--8<---------------cut here---------------start------------->8---
;; sorting the summary buffer
(setq gnus-thread-sort-functions
      '((not gnus-thread-sort-by-most-recent-number)))
--8<---------------cut here---------------end--------------->8---

What's wrong with this?

Best regards and many thanks for your help,
  Seb

-- 
Sébastien Vauban