gnus: how to redefine a keymap

[Francis Moreau <francis.moro@gmail.com>]

hello,

I'd like to redefine the 'g' key in the group buffer so it queries
only groups with a specific level or lower.

To do that I tried this:

(defun my-gnus-group-get-new-news ()
  (interactive)
  (gnus-group-get-new-news 2))

(add-hook 'gnus-group-mode-hook
          (lambda ()
            (define-key gnus-group-mode-map
              [g] 'my-gnus-group-get-new-news)))

but it doesn't work.

If I map my-gnus-group-get-new-news function to 'F6' for example it
works.

Could anybody tell me why it doesn't work with 'g' key ?

Thanks