XML_XPath not inheriting from common

I will probably kick myself for not figuring this one out but for some reason when I instantiate the XML_XPath class and attempt to call a function from XML_XPath_common I receive "Call to undefined function: (any method name from common)". An example of the code: // include class require_once("XML/XPath.php"); // instantiate object $tre = new XML_XPath("/path/to/valid/file/samples.xml"); $t = $tre->getElementsByTagName("Description"); Shouldn't the getElementsByTagName be accessible through the $tre object handler? Thanks, J -- "If there's a World War III, World War IV will be fought with sticks and stones."