This code generates an "objected expected" error when I select the unselected option in the list.

Code:
<html><head>
<script type="text/javascript">
function wgxx() {
    var temp = getElementById ("zzzz");
}
</script>
</head><body>
<form action="abcd.php">
    <select id="zzzz" onChange="wgxx()">
    <option>1</option>
    <option>2</option>
    </select>
</form>
</body></html>
Does anyone have any idea why this is happening?