problem with IE

i have the following function

function setOutput(){
	if(httpObject.readyState == 4){
	var select = document.getElementById("category_2");
	select.options.length = 0;
		for (i in httpObject.responseXML.getElementsByTagName("category")) {		
				select.options[select.options.length] = new Option(httpObject.responseXML.getElementsByTagName("name")[i].firstChild.nodeValue, httpObject.responseXML.getElementsByTagName("id")[i].firstChild.nodeValue);	
		}
		
    return
	}
}

Code (markup):

this is the structure of the file i call

header('Content-Type: text/xml');
echo "<?xml version=\"1.0\" encoding=\"iso-8859-8-i\" ?>";
echo "<rss version=\"2.0\">";
......
......
......
while ($selected = mysql_fetch_array($query)) {
	echo "<category>";
	echo "<name> {$selected['name']} </name>";
	echo "<id> {$selected['id']} </id>";
	echo "<final> {$selected['final']} </final>";
	echo "</category>";
}
echo "</rss>";

Code (markup):

it works fine on firefox but i have that yellow 'error on page' icon whn trying
to run it on ie.
it probably has something to do with 'getElementsByTagName' method
because it gives me no errors if i remove the for loop and changing the new option values into a simple text