Why doesn't it work right to upload the photo's and show them? i like the gallery but if ain't not working i cant use it :S
http://www.kps-designs.nl/zenphoto/

Did setup complain about anything? Are the permissions set correctly? Are there errors in your error log? Besides that the highslide theme is not one of the official themes and not officially supported so may not work correctly (the highslide functionality is probably not working).

Your URL is not working because of some kind of security problem on your website.