Old messages missing on the present newsgroup

[Rodolfo Medina]

Hi.

Some old messages sent to the present newsgroup
are not accessible, it seems, if I search for them via
nntp server, whereas they're seen through web interface
and also in the archives of the info-gnus-english@gnu.org mailing list.
How come?
For example, the whole thread 'nntp (bla bla) open error', started on the
12 september 2004, is visible at:

http://groups.google.com/group/gnu.emacs.gnus/browse_thread/thread/6bb69dcdf1548e17/10c9d5f223a33d19?q=medina&rnum=4#10c9d5f223a33d19

, and also at:

http://lists.gnu.org/archive/html/info-gnus-english/2004-09/msg00114.html

, whereas I can't fetch it using gnus, neither at 
'nntp+news.gmane.org:gmane.emacs.gnus.user' nor at
'nntp+news.gnus.org:gnu.emacs.gnus'.

Other threads are only partially accessible via nntp.

Any thought/suggestion?
Maybe there are some other nntp servers to read the present newsgroup,
besides news.gmane.org and news.gnus.org?

Thanks,
Rodolfo