Why does media wiki install stop?

I am building a new MediaWiki installation on a CentOS 6.4 system. Server version: Apache/2.2.15 (Unix) Server built: May 13 2013 22:11:16 PHP 5.3.3 (cli) (built: Feb 22 2013 02:51:11) Copyright (c) 1997-2010 The PHP Group Zend Engine v2.3.0, Copyright (c) 1998-2010 Zend Technologies MediaWiki 1.21.1 mysql Ver 14.14 Distrib 5.1.69, for redhat-linux-gnu (x86_64) using readline 5.1 I can reach the index.php page and get this message MediaWiki 1.21.1 LocalSettings.php not found. Please set up the wiki first. When I click on the Please set up the wiki first. hyperlink, This is the URL, which is correct. http://appcentral:8587/mw-config/index.php The page stays blank, and nothing happens. What should I check to see what is going wrong. This is a fresh, clean installation. There is no existing MySQL DB already setup for the wiki. Here is the error in error.log under /var/log/httpd. PHP Fatal error: Class 'DOMDocument' not found in /var/www/arlington_it/includes/cache/LocalisationCache.php on line 546, referer: http://localhost:8587/index.php