JS调用CSS滤镜问题 - 编程论坛

请大家帮忙看看那以下代码哪有问题啊,总是报filters.alpha为空或不是对象....

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.
<html xmlns="http://www.
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>通过层实现淡出淡入</title>
<script>
    function makevisible(cur,which)
    {
        alert("this event is successfully trigger !!!")
        if(which==0)
        {    cur.filters.alpha.opacity=100;}
        else
        {    cur.filters.alpha.opacity=50;}
    }
</script>
</head>

<body>
    <div id="fade" style="width:200px;height:200px;fitler:alpha(opacity=50);border:1px solid #000; background:#efefef" onMouseOver=makevisible(this, 0) onMouseOut=makevisible(this,1)>Saint Michael Owen</div>

</body>
</html>