API data not displayed in IE and Firefox

I have an xml API that renders correctly in google chrome but in IE and Firefox, the data is not displayed. Are there any tweaks to make it work in IE and Firefox. if so please provide relevant script or code. Thanks in advance
code--------------------------------------------------------------------------------------
if (window.XMLHttpRequest) {
//Firefox, Opera, IE7, and other browsers will use the native object
var xmlhttp = new XMLHttpRequest();
} else {
//IE 5 and 6 will use the ActiveX control
var xmlhttp = new ActiveXObject("Microsoft.XMLHTTP");
}
xmlhttp.open("GET","url link",false);
xmlhttp.send();
xmlhttp=xmlhttp.responseXML;
document.write("");
var x=xmlhttp.getElementsByTagName("offers");
for (i=0;i