the "Optional comment about this change:" text area is not showing up on my wiki when I edit pages.  I just see the label "Optional comment about this change:" and no box in which to put the comment.

Is it possible I turned this off by messing around with plugins?  Even if so, then it's strange that I see the "optional comment" text without the corresponding text area.

If the answer isn't immediately obvious you can see for yourself at http://metameso.org/aa/ikiwiki.cgi?page=index&do=edit (UN: guest PW: guest2011).