[Plugin: Header Slideshow] Isn't working

Hi there. I downloaded this plugin and did everything it said to. I edited the .xml file with the URL’s of my images, and when I activated the plugin, there is a white box in place of the images. I can see a gray fade across the box as the image “refreshes” and changes images according to the time I set, so the issue seems to be with displaying the images.

Thanks in advance!

http://wordpress.org/extend/plugins/header-slideshow/