Estoy dibujando una ruta simple desde una fuente a un destino usando el Servicio de Direcciones de Google Maps V3.

Necesito agregar algunas ubicaciones (puntos medios o waypoints) por los que la ruta debe pasar. Google Maps proporciona puntos de referencia para esto.

Me he referido a sudocumentación y ejemplo para agregar waypoints. Pero cuando intento dibujar la ruta agregando waypoints, la ruta se muestra solo desdeúltima ubicación añadido en la matriz de puntos de referencia a ladestino. Quiero que se muestre la ruta desdesrc adestino con waypoints incluidos a lo largo de la ruta.

He adjuntado mi código. ¿A dónde me estoy yendo mal?

        var map;
        var wyPts = [];



    function addWayPoints(location)
    {           
        wyPts.push({
            location:location,
            stopover:true
            });
    }

    function createInfoWindowContent(latLng, contentStr) {
        var content = '<p><b>' + contentStr + ' </b> </p>' + 'LatLng: ' + latLng    ;
        return content;
    }


    function displayRoute(origin, destination, service, display) {
        service.route({
            origin : origin,
            destination : destination,
            //waypoints: [{location: new google.maps.LatLng(30.439025, -97.685654)}, {location: new google.maps.LatLng(30.434882, -97.677015)} , {location:new google.maps.LatLng(30.429495, -97.675274)}],
            waypoints:wyPts,
            optimizeWaypoints: true,
            travelMode : google.maps.DirectionsTravelMode.DRIVING       
        }, function(response, status) {
            if (status === google.maps.DirectionsStatus.OK) {
                display.setDirections(response);
            } else {
                alert('Could not display directions due to: ' + status);

            }
        });
    }


    function initMap() {


        //////////source  destination and middle waypoints

        var src = new google.maps.LatLng(30.444719, -97.686202); // //school
            //addWayPoints(src);
        var midPt1 = new google.maps.LatLng(30.439025, -97.685654); // 
            addWayPoints(midPt1);
        var midPt2 = new google.maps.LatLng(30.434882, -97.677015); // 
            addWayPoints(midPt2);
        var midPt3 = new google.maps.LatLng(30.429495, -97.675274); // 
            addWayPoints(midPt3);


            /* for (var i = 0; i < wyPts.length; i++) {
                alert("pts are : " + wyPts[i].location);
            } */

        var destination = new google.maps.LatLng(30.401820, -97.669545); //


        ///////////draw the map
        map = new google.maps.Map(document.getElementById('map'), {
            center : src,
            mapTypeControlOptions : {
                style : google.maps.MapTypeControlStyle.HORIZONTAL_BAR,
                position : google.maps.ControlPosition.TOP_RIGHT,
                mapTypeIds : [ google.maps.MapTypeId.ROADMAP,
                        google.maps.MapTypeId.TERRAIN,
                        google.maps.MapTypeId.HYBRID ]
            },
            zoomControl : true,
            zoomControlOptions : {
                position : google.maps.ControlPosition.RIGHT_CENTER
            },
            zoom : 14
        });

        //draw infowindow at src and destination
         var coordInfoWindowSrc = new google.maps.InfoWindow({
            content: createInfoWindowContent(src , "Source"),
            maxWidth : 180
        });
        coordInfoWindowSrc.setPosition(src);
        coordInfoWindowSrc.open(map);

         var coordInfoWindowDest = new google.maps.InfoWindow({
            content: createInfoWindowContent(destination , "Destination"),
            maxWidth : 180
        });
        coordInfoWindowDest.setPosition(destination);
        coordInfoWindowDest.open(map);


        //display route
        var polylineProps = new google.maps.Polyline({
            strokeColor : '#009933',
            strokeOpacity : 1.0,
            strokeWeight : 3

        });


        var directionsDisplay = new google.maps.DirectionsRenderer({
            draggable : false, //do not make the route draggable
            map : map,
            suppressMarkers: true ,
            polylineOptions : polylineProps
        });

        var directionsService = new google.maps.DirectionsService();

        displayRoute(src, destination, directionsService,directionsDisplay);

        //add listener to map
        directionsDisplay.addListener(
                'change',
                function() {
                    displayRoute(src, destination, directionsService,
                            directionsDisplay);
                });


    }

Gracias por adelantado.