大家帮忙看看，为什么没有滚动效果？
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style type="text/css">
*{
margin:0;
padding:0;
}
#obox {
width:400px;
height:300px;
margin:0 auto;
border:1px solid #333;
margin-top:50px;
overflow:hidden;
}
#moocBox {
width:300px;
height:470px;
margin:0 auto;
}
li {
list-style:none;
line-height:30px;
font-size:12px;
}
</style>
<script type="text/javascript">
var area = document.getElementById('moocBox');
var con1 = document.getElementById('con1');
var con2 = document.getElementById('con2');
var speed = 50;
area.scrollTop = 0;
con2.innerHTML = con1.innerHTML;
function scrollUp(){
if(area.scrollTop >= con1.scrollHeight) {
area.scrollTop = 0;
}else{
area.scrollTop ++;
}
}
var myScroll = setInterval("scrollUp()",speed);
area.onmouseover = function(){
clearInterval(myScroll);
}
area.onmouseout = function(){
myScroll = setInterval("scrollUp()",speed);
}
</script>
</head>
<body>
<div id="obox">
<div id="moocBox">
<ul id="con1">
<li><a href="#">1.学会html5 绝对的屌丝逆袭（案例）</a><span>2013-09-18</span></li>
<li><a href="#">2.tab页面切换效果（案例）</a><span>2013-10-09</span></li>
<li><a href="#">3.圆角水晶按钮制作（案例）</a><span>2013-10-21</span></li>
<li><a href="#">4.HTML+CSS基础课程(系列)</a><span>2013-11-01</span></li>
<li><a href="#">5.分页页码制作（案例）</a><span>2013-11-06</span></li>
<li><a href="#">6.导航条菜单的制作（案例）</a><span>2013-11-08</span></li>
<li><a href="#">7.信息列表制作(案例)</a><span>2013-11-15</span></li>
<li><a href="#">8.下拉菜单制作(案例)</a><span>2013-11-22</span></li>
<li><a href="#">9.如何实现“新手引导”效果</a><span>2013-12-06</span></li>
<li><a href="#">10.导航条菜单的制作（案例）</a><span>2013-11-08</span></li>
<li><a href="#">11.信息列表制作(案例)</a><span>2013-11-15</span></li>
<li><a href="#">12.下拉菜单制作(案例)</a><span>2013-11-22</span></li>
<li><a href="#">13.如何实现“新手引导”效果</a><span>2013-12-06</span></li>
</ul>
<ul id="con2">
</ul>
</div>
</div>
</body>
</html>
