getElementById in AJAX

I am loading files via AJAX and the getElementById method seems to be missing in IE6. I just need to check.

var func = function(request) {
  if(request.readyState == 4 && request.status == 200) {
    debug("  Request response is: " + request.responseXML + " (" + typeof(request.responseXML) + ")");
    if(request.responseXML) {
      debug("Parse Error: " + request.responseXML.parseError);
      try {
        var propCount = 0;
        for(var prop in request.responseXML) {
          propCount++;
        }
        debug("Response XML Property Count: " + propCount);
      } catch(e) {
        debug("Error: (" + prop + ") [" + propCount + "]: " + e);
      }
      debug("  getElementById is: " + typeof(request.responseXML.getElementById));
      var children = "Child Nodes: (" + request.responseXML.childNodes.length + ")";
      for(var i = 0; i < request.responseXML.childNodes.length; i++) {
        children += " [" + i + "] = " + request.responseXML.childNodes.item(i).nodeName;
        children += (" (" + request.responseXML.childNodes.item(i).nodeType + ":" +
                     request.responseXML.childNodes.item(i).childNodes.length + ")");
      }
      debug(children);
      if(request.responseXML.documentElement) {
        debug("Document Element: " + request.responseXML.documentElement.nodeName);
        if(typeof(request.responseXML.documentElement.selectNodes) != "undefined") {
          request.responseXML.setProperty
            ("SelectionNamespaces",
             "xmlns:html='http://www.w3.org/1999/xhtml'");
          var nodes = request.responseXML.documentElement.selectNodes("//html:body");
          debug("html:body nodes found with selectNodes: " + nodes.length);
        } else if(request.responseXML.createNSResolver) {
          var nodes = request.responseXML.evaluate
           ("//html:body",
            request.responseXML,
            { normalResolver: request.responseXML.createNSResolver(request.responseXML.documentElement),
              lookupNamespaceURI: function(prefix) {
                switch(prefix) {
                  case "html": return "http://www.w3.org/1999/xhtml";
                  default: return this.normalResolver.lookupNamespaceURI(prefix);
                }
              }
            },
            XPathResult.ORDERED_NODE_SNAPSHOT_TYPE,
            null);
          debug("html:body nodes found with evaluate: " + nodes.snapshotLength);
        }
      }
    }
    debugBreak();
  }
}
loadXMLDocument(window.location.pathname, func);
loadXMLDocument(window.location.pathname.replace(/\.[^\.]+$/, ".xml"), func);