Facebook Open Graph giving error "Can't download: Could not retrieve data from URL" and status code 206

This works:

http://www.opengraph.in/?url=snakes.eric-wieser.tk/fb-og.html

But this doesn't:

http://developers.facebook.com/tools/debug/og/object?q=snakes.eric-wieser.tk/fb-og.html

The page being scraped is here. I don't think I can make it much simpler

Facebook gives a status 206, and says it can't download any data from the page.

I'm using Express and Node.js, set up like this:

var app = express.createServer();
app.listen(8090);
app.use(express.static(__dirname, {maxAge: 60000}));

Why isn't it working? What ca