Google Maps getBounds()返回undefined

我正在写一个代码,它将:

- 加载地图并将其置于KML中心

- 根据地图的边界绘制多边形.

这里是代码.我收到一个错误

未捕获的TypeError:无法调用未定义的方法'getNorthEast'

    function initialize()
{
    var mapOptions =
    {
    zoom: 19,
    mapTypeId: google.maps.MapTypeId.ROADMAP //higer zoom
    };

    var KML1 = new google.maps.KmlLayer(
            {
            clickable: false,
            url: 'https://s3.amazonaws.com/navizon.its.fp/1001/f43l9uvts1_a.kml' //kml link for the floor-plan
            });
    var map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
    KML1.setMap(map);


    var bounds = new google.maps.LatLngBounds();
    bounds = map.getBounds();
    var ne = bounds.getNorthEast();
    var sw = bounds.getSouthWest();

    var QLat = Math.abs((ne.lat()-sw.lat())/5);
    var QLng = Math.abs((sw.lng()-ne.lng())/5);

    var swLat = sw.lat()+QLat;
    var swLng = sw.lng()+QLng;

    var neLat = ne.lat()-QLat;
    var neLng = ne.lng()-QLng;

    ne = new google.maps.LatLng(neLat,neLng);
    sw = new google.maps.LatLng(swLat,swLng);

    var Coords = [
                ne, new google.maps.LatLng(ne.lat(), sw.lng()),
                sw, new google.maps.LatLng(sw.lat(), ne.lng()), ne
            ];


    surface = new google.maps.Polygon(
    {
    paths: Coords,
    strokeColor: '#00AAFF',
    strokeOpacity: 0.6,
    strokeWeight: 2,
    fillColor: '#00CC66',
    fillOpacity: 0.15,
    editable: true,
    draggable: true,
    geodesic:true
    });

    surface.setMap(map);
    google.maps.event.addListener(surface, 'mousemove', ciao) //add listener for changes
    //$("#results").append(coordinates[0]);
  //Let's update area and price as the poly changes
function ciao(event)
{
        var vertices = this.getPath();
        // Iterate over the vertices.
        for (var i =0; i < vertices.getLength(); i++) {
            var xy = vertices.getAt(i);
            Coords = []
            Coords.push(xy);  
            };
}
}

有什么建议吗？

谢谢,

丹尼尔