Getting javascript errors

Hi

I keep getting a TypeError: Result of expression 'options' is not an object.

on this javascript

    function ajxCastVote(){

        var xhr = getXhr();

        xhr.onreadystatechange = function(){

            if(xhr.readyState == 4 && (xhr.status == 200 || xhr.status == 404)){

                try //Internet Explorer

                {

                    xmlDoc=new ActiveXObject("Microsoft.XMLDOM");

                    xmlDoc.async="false";

                    xmlDoc.loadXML(xhr.responseText);

                }

                catch(e)

                {

                    try //Firefox, Mozilla, Opera, etc.

                    {

                        parser=new DOMParser();

                        xmlDoc=parser.parseFromString(xhr.responseText,"text/xml");

                    }

                    catch(e) {alert(e.message)}

                }



                var options =xmlDoc.getElementsByTagName('options').item(0);

                if(options == null){

                    options = xmlDoc.getElementsByTagName('errormsg').item(0);

                    var error = options.childNodes[0].nodeValue;

                    document.getElementById('loadingImg').style.display = 'none';

                    alert(error);

                    return;

                }

                updatePieChart(options,'Henter resultaterne.....');                updateWrapper();

            }

        }



        optionid = getSelectedValue();

        if(optionid == null){

            alert('Du mangler at tage en valgmulighed.');

            return;

        }

        document.getElementById('loadingImg').style.display = '';

        xhr.open("GET","index.php?option=com_communitypolls&controller=polls&task=ajxvote&id="+

            2+"&option_id=" + optionid,true);

        xhr.send(null);

        requestSent = true;

    }

To be specific, this is the line that my "debugger" complains about:

options = xmlDoc.getElementsByTagName('errormsg').item(0);

The result is, I cannot vote on any polls. Any advise?