利用单选按钮控制层的出现,该怎么解决

利用单选按钮控制层的出现
<script   language= "javascript ">
function   change_view(obj_name1,obj_name2)
{
var   aa=document.getElementById(obj_name1);
aa.style.display= " ";
var   bb=document.getElementById(obj_name2);
bb.style.display= "none ";
}
</script>
<div   id= "up1 "   style= "display:none; "> 1 </div>
<div   id= "up2 "   style= "display:none; "> 2 </div>

<input   type= "radio "   value= "shao "   name= "radio "   onclick= "javascript:change_view( 'up1,up2 '); "   />
<input   type= "radio "   value= "duo "   name= "radio "   onclick= "javascript:change_view( 'up2,up1 '); "   />
想达到的目的是点击单选按钮1，up1出现，up2隐藏，点击单选按钮2，up1隐藏，up2出现

这样写运行时出错，谁帮忙看看。

[解决办法]
change_view( 'up1 ', 'up2 ')
另一个同理
[解决办法]
javascript:change_view( 'up1 ', 'up2 ');