Reassigning the tab key in topic mode

[jeff.rancier@softechnics.com (Jeffery B. Rancier)]

I'm trying to reassign the function of the tab key while in topic mode
in the group buffer (without any luck).  Here what I have added to my
~/.gnus:

(defun jbr-gnus-topic-mode-hook()
  (local-set-key [tab] 'gnus-group-next-unread-group)
  (jbr-pause-message "Set TAB key to gnus-group-next-unread-group" ))

(add-hook 'gnus-topic-mode-hook 'jbr-gnus-topic-mode-hook)

Evaluating the above code, restarting Gnus, appears to have no effect
on this:

,----
| <tab> runs the command gnus-topic-indent
|    which is an interactive compiled Lisp function in `gnus-topic'.
| (gnus-topic-indent &optional UNINDENT)
| 
| Indent a topic -- make it a sub-topic of the previous topic.
| If UNINDENT, remove an indentation.
`----

Can I assume that the tab key is assigned after the
gnus-topic-mode-hook is run?  Should I set this to global?  Or is is
that when my function is run, I'm not in the group buffer yet?
-- 

Thanks,
Jeff
,----
| Jeffery B. Rancier
| 
| Softechnics
| a METTLER TOLEDO company
`----