Install Issue

Am installing PP onto a new Bluehost account with PHP 5. I've installed into both the public_html directory and a directory called projectpier. When I navigate to both directories, I receive this notice:

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Warning: require_once(INSTALLER_PATH/installation/steps/WelcomeStep.class.php) [function.require-once]: failed to open stream: No such file or directory in /home/personn2/public_html/installation.php on line 13

Fatal error: require_once() [function.require]: Failed opening required 'INSTALLER_PATH/installation/steps/WelcomeStep.class.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/personn2/public_html/installation.php on line 13

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Anyone have thoughts or recommendations? It could be I'm missing something.

Kevin