Not able to get the xml data into the responseXML in AJAX

I am trying to get the xml data from a jsp into the AJAX function. I only getting the xml as responseText but not as responseXML. It is showing the null value in responseXML. This is the xml data of the jsp.

<%@ page contentType="text/xml" %><?xml version="1.0" encoding="UTF-8"?>
<%@taglib uri="http://ift.tt/QfKAz6" prefix="c" %>


<itemslist>
    <c:set var="itemCodeVal" value='<%=request.getAttribute("itemDetails")%>'/>       
    <c:forEach items="${itemCodeVal}" var="entry">
        <item>
            <item_id>
                ${entry.iItemId}
            </item_id>
            <item_code>
                ${entry.strItemCode}
            </item_code>
            <item_name>
                ${entry.strItemName}
            </item_name>
            <price>
                ${entry.dPrice}
            </price>
        </item>
    </c:forEach>

And this jsp is returning to the jsp which contains the AJAX function.

  if (window.XMLHttpRequest)
            {
                xmlhttp = new XMLHttpRequest();
            }
            else
            {
                xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
            }
            xmlhttp.onreadystatechange = function ()
            {
                if (xmlhttp.readyState == 4)
                {

                        var xmlDoc = xmlhttp.responseText;
                        alert(xmlhttp.responseXML);
                        txt = "";
                        x = xmlDoc.getElementsByTagName("item");
                        for (i = 0; i < x.length; i++)
                        {
                            txt = txt + x[i].childNodes[0].nodeValue + "<br>";
                        }
                        alert(txt);



                }
            }
            xmlhttp.open("GET", urls, true);
            xmlhttp.send();

I'm not getting that xml here as responseXML but getting as reponseText. Can you Please help me how to resolve this issue.

Thanks in Advance Manoj Kumar