Sorry to sound as if im attacking you. But your on a PHP Board we are more than willing to help but why use PHPNuke?
Yes its a quick fix and yes you can be up in minutes or in your case not up at all.
Im not sure on why it isnt working maybe PHPNuke Userbase/forums can help, remember they are the creators, users and have good knowledge with the it.
On the other hand im sure you can learn PHP and build your own, it wont take as long as you think to learn PHP and build a simple CMS