Cancerbox Horizon Theme – won’t install! Why?

I’ve got a fresh, clean install of WP 2.8, hosted at my own web server. I’ve installed several themes earlier and know how to do this. However, I just downloaded the Cancerbox Horizon photoblog theme, uploaded it to wp-content/themes, and it doesn’t show up under themes. I’ve searched the forums and the net in general for answers to this, and the Cancerbox forums are down due to maintenance.

Help anyone? Anyone wanna try installing the theme to help me troubleshoot?

Please help, I’m about to give up here..