不理解动态增加object标签的错误！

<html>    
<head>   
<title></title>   
<script type="text/javascript">    
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window.onload = function(){   
var dwf = document.createElement('object');    
dwf.setAttribute("classid","clsid:A662DA7E-CCB7-4743-B71A-D817F6D575DF");    
dwf.setAttribute("codebase","http://www.autodesk.com/global/dwfviewer/installer/DwfViewerSetup.cab");    
dwf.setAttribute("width",640);    
dwf.setAttribute("height",480);    
var param = document.createElement("param");    
param.setAttribute("name","src");    
param.setAttribute("value","龙湖别院落1号.dwf");    dwf.appendChild(param);var embed = document.createElement("embed");    
embed.setAttribute("src","龙湖别院落1号.dwf");    
embed.setAttribute("quality","high");    
embed.setAttribute("pluginspage","http://www.macromedia.com/go/getflashplayer");    
embed.setAttribute("type","application/x-shockwave-flash");   
embed.setAttribute("width",640);   
embed.setAttribute("height",480);   dwf.appendChild(embed);  document.body.appendChild(dwf);    
};   
//-->    
</script>    
</head>   
<body>   
</body>    
</html>