GetUrl won't open in same window?

Question

Hello,
I am creating a website with a flash menu on each page. I am using getUrl code to target each page but I can't seem to get the pages to open in the same window. If I use '_new' or '_blank' the pages open in a new window as they should but if I use '_self' or '_top' nothing happens.
Any help is much appreciated. Thanks!
Code: AS3
aboutBtn.buttonMode = true;
aboutBtn.addEventListener(MouseEvent.CLICK, callAbout);
function callAbout(e:MouseEvent):void{
  var url:String = "about.html";
  var request:URLRequest = new URLRequest(url);
  try {
    navigateToURL(request, '_self');
  } catch (e:Error) {
    trace("Error occurred!");

Answer 1

I think I have the right code this time but it's still not working. I tried it on a Mac and it works fine but it is no working on PC (Windows). Any idea why?
Thanks,
Dan
aboutBtn.buttonMode = true;
aboutBtn.addEventListener(MouseEvent.CLICK, callAbout);
function callAbout(e:MouseEvent):void{
    var link:URLRequest = new URLRequest("about.html");
    navigateToURL(link, '_self');