Weird XML loading problems

I am having very strange problems with my XML in Flash. Its ok to view running off my computer but when I upload it to my server and then open it the XML doesnt load. Below is by AS so you can check it…

this.xmlData = new XML();
this.xmlData.ignoreWhite = true;
this.xmlData.onLoad = loadXML;
function loadXML(loaded) {
    if (loaded) {
        title = "<u>" + this.lastChild.childNodes[0].childNodes[nodeNum].childNodes[0].lastChild.nodeValue + "</u>";
        desc = this.lastChild.childNodes[0].childNodes[nodeNum].childNodes[2].lastChild.nodeValue;
        linkurl = this.lastChild.childNodes[0].childNodes[nodeNum].childNodes[1].lastChild.nodeValue;
        xmltitle.titletxt = title;
        desc = desc;
            nextNode = this.lastChild.childNodes[0].childNodes[nodeNum+1].childNodes[0].lastChild.nodeValue;
                previousNode = nodeNum - startNode;
    } else {
        this.desc = "File did not load!";

The codes fine its just when its on the net…help needed urgently please.