Vil ikke virke i IE - (AJAX)

Kode 

//PÅ MASTERPAGE

<script type="text/javascript">
function skift_sprog()
{
	var xmlHttp;
	try
	{
		// Firefox, Opera 8.0+, Safari
		xmlHttp=new XMLHttpRequest();
	}
	catch (e)
	{
		// Internet Explorer
		try
		{
			xmlHttp=new ActiveXObject("Msxml2.XMLHTTP");
		}
		catch (e)
		{
			try
			{
			xmlHttp=new ActiveXObject("Microsoft.XMLHTTP");
			}
			catch (e)
			{
			alert("Your browser does not support AJAX!");
			return false;
			}
		}
	}
	
	xmlHttp.onreadystatechange=function()
	{
		if(xmlHttp.readyState==4)
		{
			window.location.reload( false );
		}
	}
	
	xmlHttp.open("GET","scripts/sprog/select.php?skift=ja&sprog="+document.getElementById('sprog_skifter').value,true);
	xmlHttp.send(null);
}

</script>

//PÅ REQUIRED / INCLUDED SIDE

<form>
	<select id="sprog_skifter">
		<option onMouseUp="skift_sprog();" value="da">Dansk</option>
		<option onMouseUp="skift_sprog();" value="en">English</option>
	</select>
</form>