PDF Not working

Whenever I try to view the PDF it gives me an error saying:

The image "http://www.hot1047.com/administrator/components/com_joomla-visites/index.php?site=1&date=2007-10-02&period=1&mod=view_pdf&rss_hash=d41d8cd98f00b204e9800998ecf8427e" cannot be displayed, because it contains errors.

What's causing this?