That particular host has phpinfo disabled, it's in their FAQ.

The problem you are having is that you can't access the forum cp? You are using a theme from here, and Splatt forum. These themes wont work with Splatt forum, they are written for phpbb port.

Are you sure the forum is Splatt? You can't access phpbb forum cp through the icon in the nuke admin cp. You have to do it through the link at the bottom of the forum index page.