Error for load DropDownList

Error for load DropDownList

i have problem in my code for load one dropdown list.

my code is down.
function TrazComarcaSelec(tribunal) {
    //alert("Função Chamada" + tribunal);
    var url = "ajaxTrazComarca.asp?trn=" + tribunal;
    try {
        // alert(url);
        $.get(url, function(xml) {
            // alert("Função sendo executada");
            $("#loadCom").show('show');
            var xml2 = $("tribunais", xml);
            var com = $("#ComarcaBB");
            com.empty();
            xml2.find("Comarcas").each(function() {
                var nOption = $(document.createElement("option"))
               .val($(this).attr("CD_CMR"))
               .append(this.childNodes[0].nodeValue);
                com.append(nOption);
            }
            );
        });
    }
    catch (e) {alert(e.message);}
}

help-me please

Bruno Capella