[O] todo autochange to done

[scrawler]

Hey guys,

In the manual, section 5.5, there is a function shown that would allow a "TODO 
entry to automatically change to DONE when all children are done". Here it is:

;>>>>>

(defun org-summary-todo (n-done n-not-done)
 "Switch entry to DONE when all subentries are done, to TODO otherwise."
 (let (org-log-done org-log-states)
                                        ; turn off logging
   (org-todo (if (= n-not-done 0) "finished" ":-)"))))
(add-hook ’org-after-todo-statistics-hook ’org-summary-todo)

;<<<<<

I get this:
Symbol's value as variable is void: ’org-after-todo-statistics-hook

What's going on?
thanks!
-- 
signature to baby: "doobywoobybooboo"
:-)