var rules_pdi = [];
function generate_rules_pdi() {

    for (var i = 0; i < (pdi_layer.features-lenght); i++) {

        rules_pdi[i] = new OpenLayers.Rule({
                    title: "${name}", <------------------------ does not work
                    filter: new OpenLayers.Filter.Comparison({
                        type: OpenLayers.Filter.Comparison.EQUAL_TO,
                        property: "id",
                        value: "${id}" <---------------------------does not work
                    }),
                    symbolizer: {
                        label: "${name}", <-----------------------------work
                        graphicWidth: 30,
                        graphicHeight: 30,
                        graphicYOffset: -26,
                        graphicOpacity: 1,
                        externalGraphic: "../../img/simbologia_layers/pdi/" + "${id}" + ".png"
                    }
                })
    }

    return rules_pdi;
}