DOM/XML -> PHP 5.0.3 HowTo?

Hi list, i took this tutorial for creating xml file from scratch. toturial is is present at sitepoint. www.sitepoint.com/print/management-system-php. ok i dont know how to enable DOM/XML feature, when i do phpinfo(); it does give that DOM/XML is enable but i cant run this tutorial. i try to debug and found out that i cant create document root. ie. $doc = domxml_new_doc("1.0"); [this part comes when u create addArticle.php file]it gives me blank page. any idea what is wrong? my configuration is webserver: Apache 2.0.53 php: PHP 5.0.3 thx in advance. Faisal