Ajax response issue in Chrome

Question

I am working on a old piece of Ajax code which works fine with IE (i.e i am getting proper XML response) but with Chrome, I am getting null XML response (in fact responseText is also blank). When i debugged the issue with Chrome, i realized that when reqAJAX.readyState == 3, i see some XML response which gets nulled out as soon as reqAJAX.readyState equals 4.

Here is code snippet :

function jsAJAX(strRequestType, strRequestParams) {
    if (window.XMLHttpRequest) { 
        reqAJAX = new XMLHttpRequest(); 
    } else if (window.ActiveXObject) {
        reqAJAX = new ActiveXObject("Microsoft.XMLHTTP"); 
    }

    reqAJAX.onreadystatechange = jsData;
    reqAJAX.open("POST", "../AnnouncementData.aspx", true);        
    reqAJAX.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
    var reqAJAXParams = "AjaxReqData=ab%7CIBM";
    reqAJAX.send(reqAJAXParams);
}

function jsData() {
    if (reqAJAX.readyState == 4) {        
        if (reqAJAX.status == 200) {
            var rspDoc = reqAJAX.responseXML.documentElement;
            alert(rspDoc);
        }
    }
}