自己写了一下html/css,但加上js后执行不了，希望大家帮忙看看
<!DOCTYPE HTML>
<html>
<head>
<title>滚动栏</title>
<style type="text/css">
*{margin:0;
padding:0;}
a:link{color:black;text-decoration:none;}
a:visited{color:black;text-decoration:none;}
a:hover{color:red;text-decoration:none;}
.imooc{height:px;
width:400px;
margin:0 auto;
border:2px solid black;
border-radius: 15px;
position:relative;
top:50px;
}
.imooc .new{background:#f05e6f;
height:70px;
border-top-left-radius:15px;
border-top-right-radius:15px;
color:#fff;
}
.imooc .new h1{padding:5px 0 0 8px;;
}
.imooc .new p{float:right;
margin-bottom:10px;
}
.imooc .newclass ul{list-style:none;
font-size:12px;
}
.imooc .newclass ul li{padding:5px 0 5px 20px;
}
.imooc .newclass ul span{float:right;
padding-right:30px;
color:#ababab;
}
</style>
</head>
<body>
<div class="imooc">
<div class="new">
<h1>最新课程</h1>
<p>更多>></p>
</div>
<div class="newclass">
<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>
</ul>
<ul id="con2">
</ul>
</div>
</div>
<script type="text/javascript">
var area = document.getElementById('newclass');
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 = 10;
}else{
area.scrollTop ++;
}
}
var myScroll = setInterval("scrollUp()",speed);
area.onmouseover = function(){
clearInterval(myScroll);
}
area.onmouseout = function(){
myScroll = setInterval("scrollUp()",speed);
}
</script>
</body>
</html>谷歌浏览器报错为：Cannot set property 'scrollTop' of null
可能是我的css代码有问题，但个人能力有限，希望大家帮我看下
