Getting a thumbnail with xpath

Hi there, I've got a basic Foodspotting action stream working, but can't figure out why I can't get a thumbnail. It seems like the url to the image is not being picked up.

Here's how I'm trying to grab the thumbnail:

xpath:
foreach: //item
get:
created_on: pubDate/child::text()
url: link/child::text()
title: title/child::text()
thumbnail: media:thumbnail/@url

And here's a link to the XML/RSS I'm working with:

http://www.foodspotting.com/115648-peter-leonard.rss

Theories... the media: namespace has to be declared somehow? (But other sample code from SA does not do this either) Or the media:thumbnail is improperly non-nested within a media:content tag in Foodspotting's output?

thanks for any ideas!