As you have not explicitly set a configUrl or baseUrl in your gallery's embedding code, Juicebox will, by default, look for your gallery's XML file to be named 'config.xml' and to be located in the same directory as the HTML page which contains the embedding code.
Therefore, your gallery's XML file should be located here: http://www.website-design.ca/exhibition/config.xml
... but it does not seem to be there. Going directly to this location in a browser results in an error 404 (file not found).
Upload your 'config.xml' file to your 'exhibition' directory and your gallery should display fine (as long as the paths within the XML file are correct).
If you want to rename or relocate your gallery's XML file, you can do so using the configUrl configuration option.
For example:
<!--START JUICEBOX EMBED-->
<script src="jbcore/juicebox.js"></script>
<script>
new juicebox({
configUrl: "/gallery/custom.xml",
containerId: "juicebox-container",
galleryWidth: "100%",
galleryHeight: "100%",
backgroundColor: "#222222"
});
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->