[Orgmode] Using [/] or [%]

[David Ellis]

The manual includes the following:

To keep
the overview over the fraction of subtasks that are already completed, insert
either ‘[/]’ or ‘[%]’ anywhere in the headline.  These cookies will
be updates each time the todo status of a child changes.  For example:

     * Organize Party [33%]
     ** TODO Call people [1/2]
     *** TODO Peter
     *** DONE Sarah
     ** TODO Buy food
     ** DONE Talk to neighbor
This seems to mean that if I enter the following into an org file:
** TODO test3 [/]
*** TODO test 1
*** TODO test 2
*** TODO test 3
the [/] should be updated as I mark the sub tasks done. This doesn't work for me.

I can get [/] and [%] to work with checkboxes. Is there some variable that I need to set to get this to work?

Dave Ellis