No sortable column headers

I’m trying to embed a plugin to my page http://www.care2.com/care2blog/take-action-platform-target-petitions

However the column headers are not sortable. What do I need to do to make the headers sortable?

I’m using the following shortcode
[gdoc key=”docs.google.com/url_removed” class=”my-sheet” title=”Available Petitions to promote” summary=”A list of available petitions for promotion.”]A list of available petitions to promote.[/gdoc]