Code $("ul").prev("li") doesn't work in IE. Opera & Firefox work as expected. Code below demostrates the error: "li" tags are not marked by red color in IE.

<script src="jquery-1.2.3.js"></script>

<ul>
  <li id="1">aaa</li>
  <li id="2">bbb</li>
  <ul>
    <li>ccc</li>
    <li>ddd</li>
  </ul>
  <li>eee</li>
  <ul>
    <li>ccc</li>
    <li>ddd</li>
  </ul>
</ul>

<script>
 $(document).ready(function() {
   $("ul").css("color", "blue").prev("li").css("color", "red");
 });
</script>