Openlayers 3 how to add kml vector from a string variable

[Rey Jaropay]

  var kmlString = result;

            

            var features = new ol.format.KML().readFeatures(kmlString, {

                dataProjection: 'EPSG:4326'

                

            });

            var KMLvectorSource = new ol.source.Vector({});

            var KMLvector = new ol.layer.Vector({

                source: KMLvectorSource,

                visible: true

            });

            KMLvectorSource.addFeature(features);

            map.addLayer(KMLvector);

hi guyz I'm trying to get a KMLlayer that returns a geometry of polygon and i catch it to a string

i did the code above as i research but it doesn't work