Why insertElement() method does not work in IE6?

Hi, I used this kind of javascript to insert text into ckeditor:

<script src="../javascript/jquery.js" type="text/javascript"></script>
<script src="../ckeditor/ckeditor.js" type="text/javascript"></script>

<script type="text/javascript">
$(document).ready(function() {
CKEDITOR.replace('lin');

$('#b').click(function() {
var element = CKEDITOR.dom.element.createFromHtml('<span>insert text</span>');
CKEDITOR.instances.lin.insertElement(element);});

});
</script>

<div>

<textarea rows="2" cols="20" class="a" name="lin" >some text</textarea>
</div>
<br /> <div id="b">insert span</div>

This kind of code works fine in firefox and chrome, but nothing happened when I click the "#b" div in ie6.

Please help me...