Why does this code not produce a dropdown list when onmouseover happens?

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 TRANSITIONAL//EN">
<html>

<head>
<style type="text/css">

div.dg
{

border:2px solid white;
display:none;
}



a
{
width: 100px;
text-align:center;
background-color:red;
color:white;
font-size:16px;
display:block;

}


</style>


</head>

<body>

<div>
<a id="kj" href="kkjklj.com" onmouseover="this.parentNode.childNodes[1].style.display='inline';"
onmouseout="this.parentNode.childNodes[1].style.display='none';">kjlj</a>
<div class="dg">
<a href="kjlj.com">lkjefee</a>
<a href="ehfueh.com">fheufheuih</a>
</div>
</div>




</body>
</html>