IE Error using active X object

Question

Well, I'm having trouble on creating an ActiveXObject! It works nicely on IE7 but on IE8+ it crashes the application! I'm trying to do the following:

var oXml = new ActiveXObject('Microsoft.XMLDOM');
oXml.async = false;
oXml.loadXML(document.XMLDocument.xml);

When I try to loadXML by document.XMLDocument.xml the browser says that

document.XMLDocument.xml is null or not an Object!! 

I already tried many things, like this: http://dean.edwards.name/weblog/2006/04/easy-xml/ and lot's of stuff, but couldn't make it work!! Help!!