function loadCities(postCallback,target){
    if(target == null){
        target = 'select_location.php';
    }
    var selectStates = document.getElementById('state');
    var stateId = selectStates.options[selectStates.selectedIndex].value;
    var evalCode = null;
    var selectCity = document.getElementById('city');
    // Vacio el select de ciudades y lo deshabilito:
    selectCity.options.length = 0
    selectCity.options[0] = new Option('cargando...','loading'); //!!!
    selectCity.disabled = true;
    var xmlhttpLocation = initAjax();
    xmlhttpLocation.open('GET',target+'?cargarLocalidadesPorProvincia&id_parent='+selectStates.options[selectStates.selectedIndex].value,true);
    xmlhttpLocation.send(null);
    xmlhttpLocation.onreadystatechange = function(){
        if (xmlhttpLocation.readyState == 4){
            if(xmlhttpLocation.status == 200){
                selectCity.options.length = 0
                eval(xmlhttpLocation.responseText);
                selectCity.disabled = false;
                if(postCallback != null){
                    eval(postCallback+'();');
                }
            }else{
                confirmAjaxRequestError();
            }
        }
    }
}