your example page is a moving target.
the installation of xowiki on openacs.org is quite ancient (nearly a year old). I guess, the problem was due to regexp parsing of curly braces. make sure, you have a blank before the two closing braces of the includelet definition.
note that you have to have some entries with page_order (section) set, to get a toc. I have added a few.
hope, this helps
