Can't read nodeValue from RSS

1 
Xml = "http://www.theguaz.com/blog/?feed=rss2";

//
funcionCargarNews = function (dataXml) {
	myXML2 = new XML();
	myXML2.ignoreWhite = true;
	itemsNews = new Array();
	myXML2.onLoad = function(success) {
		if (success) {
			totaldeitemsNews = this.firstChild.childNodes[0].childNodes.length;
			//
			for (u=6; u<totaldeitemsNews; u++) {
				
				
				//
				itemsNews[u]= this.firstChild.childNodes[0].childNodes[u].childNodes[7].nodeValue;
				//
				//
				trace(itemsNews[u])
		
				//	
			}
		}
	};
	myXML2.load(dataXml);
	//
	//
};
funcionCargarNews(Xml);

anyone knows why when i test that i get null in the output windows instead of the content of the node?