I'm trying to change embed src using document.getElementById.
what am i missing?

HTML Code:
<script language="JavaScript" type="text/JavaScript">

myDate = new Date();
myTD = myDate.getTimezoneOffset();
alert(myTD);
if ((myTD >= 180) && (myTD < 480)){
document.getElementById('localswf').setAttribute('src','one.swf');
}else if((myTD >=180) && (myTD < 180)){
document.getElementById('localswf').setAttribute('src','two.swf');
}else if((myTD >= -540) && (myTD < -180)){
document.getElementById('localswf').setAttribute('src','three.swf');

}else{
document.getElementById('localswf').setAttribute('src','four.swf');
}

</script>



</head>
<body>
<div> 
  <OBJECT classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=9,0,0,0" width="105" height="105  ">
    <EMBED src='one.swf' name="localswf" id="localswf" quality="high" pluginspage="http://www.macromedia.com/go/getflashplayer" type="application/x-shockwave-flash" width="105" height="105"></EMBED></OBJECT>
</div>

</body>

thanx