[jQuery] This chain works in Firefox but not in IE6?

[paceman]

Any idea why the following chain does not work in IE6, but works in
Firefox:

$new.append("<span>").children().attr("class",
"folder").append("<fieldset>").children().load("?leaf_type=" +
leaf_type, function () {
  $(this).parent().find("#addtreeform").ajaxForm(add_options);
}).append("</fieldset>").append("</span>").append("</li>");

where $new is a JQuery object.  IE6 does not report a Javascript
error, but the load is not performed.

I solved it by having the Server do most of it, shortening the JQuery
to:
$new.load("?leaf_type=" + leaf_type, function ()  {
  $(this).parent().find("#addtreeform").ajaxForm(add_options);
}).append("</fieldset>").append("</span>").append("</li>");

I assume the problem must be somewhere between (including) the
append() at the beginning to the load().  I thought JQuery works the
same in both Firefox and IE?

Thanks in advance.