标记位置不被拾取-谷歌地图API v3

所以我试图找到2个标记之间的距离。在代码中，我在左键点击上放置了一个标记，并将标记的位置保存为变量"start"。然后，我在左键单击时放置第二个标记，并将该标记的位置保存到变量末端。然后，我调用一个函数来计算标记之间的距离，但似乎getPosition()函数没有以正确的格式拾取LatLng。我有点困惑，为什么它不会工作。

代码如下所示。任何帮助都将非常感激。由于

var directionsDisplay;
var directionsService = new google.maps.DirectionsService();
var map;
var start;
var end;
var markersArray = [];
var originPlace = new google.maps.LatLng(0,0);
var destinationPlace = new google.maps.LatLng(0,0);
function initialize() {
  directionsDisplay = new google.maps.DirectionsRenderer();
  var chicago = new google.maps.LatLng(41.850033, -87.6500523);
  var mapOptions = {
    zoom:7,
    center: chicago
  }
  map = new google.maps.Map(document.getElementById('map-canvas'), mapOptions);
  directionsDisplay.setMap(map);
  google.maps.event.addListener(map,'click',function(event) { 
    placeMarker(event.latLng); 
  }); 
}
function placeMarker(location) {
  if (markersArray.length == 0) {
            marker = new google.maps.Marker({
                position: location,
                map: map,
                title: location.toString()
            });
            // add marker in markers array
            markersArray.push(marker);
            start = marker.getPosition();
            alert(start);
        }
        else if(markersArray.length == 1)
        {
             marker = new google.maps.Marker({
                position: location,
                map: map,
                title: location.toString()
            });
            // add marker in markers array
            markersArray.push(marker);
            end = marker.getPosition();
            calcRoute(start, end);
        }
        else
        {
        }
}

function calcRoute(start, end) {
  originPlace = new google.maps.LatLng(start);
  destinationPlace = new google.maps.LatLng(end);
  var service = new google.maps.DistanceMatrixService();
  service.getDistanceMatrix(
    {
        origins: [originPlace],
        destinations: [destinationPlace],
        travelMode: google.maps.TravelMode.DRIVING
    }, callback);
}
function callback(response, status) {
  if (status != google.maps.DistanceMatrixStatus.OK) {
    alert('Error was: ' + status);
  } else {
    var origins = response.originAddresses;
    var destinations = response.destinationAddresses;
    var outputDiv = document.getElementById('outputDiv');
    outputDiv.innerHTML = '';
     for (var i = 0; i < origins.length; i++) {
      var results = response.rows[i].elements;
      for (var j = 0; j < results.length; j++) {
        outputDiv.innerHTML += origins[i] + ' to ' + destinations[j]
            + ': ' + results[j].distance.text + ' in '
            + results[j].duration.text + '<br>';
      }
    }
  }
}

google.maps.event.addDomListener(window, 'load', initialize);