百度地图API,marker添加右键菜单失败

<html>
<head>
<script type="text/javascript" src="http://api.map.baidu.com/api?v=1.4"></script>
</head>
 <body>
    <div id="container"></div>
        <script type="text/javascript">
                        var map = new BMap.Map("container");
                        var point = new BMap.Point(100, 100);
                        map.centerAndZoom(point, 17);
                        var contextMenu = new BMap.ContextMenu();
                        contextMenu.addItem(new BMap.MenuItem(("添加标识"), addMarkerOnMap));
                        map.addContextMenu(contextMenu);
                function addMarkerOnMap(e) {
                        var point = new BMap.Point(e.lng, e.lat);
                        var marker = new BMap.Marker(point);
                        map.addOverlay(marker);
                        addMarkerContextMenu(marker);
                        }
                function addMarkerContextMenu(marker) {
                        var contextMenu = new BMap.ContextMenu();
                        contextMenu.addItem(new BMap.MenuItem(("查看坐标"), function () {
                                alert("hello");
                        }));
                        marker.addContextMenu(contextMenu);
                }
        </script>
</body>
</html>

通过地图的右键菜单添加marker,然后给marker添加右键菜单,marker的右键菜单无法显示。但是如下直接添加marker,然后给marker添加右键菜单,marker的右键菜单就能显示了。

<html>
<head>
<script type="text/javascript" src="http://api.map.baidu.com/api?v=1.4"></script>
</head>
 <body>
    <div id="container"></div>
        <script type="text/javascript">
                        var map = new BMap.Map("container");
                        var point = new BMap.Point(100, 100);
                        map.centerAndZoom(point, 17);
                        var point = new BMap.Point(100, 100);
                        var marker = new BMap.Marker(point);
                        map.addOverlay(marker);
                        addMarkerContextMenu(marker);
                function addMarkerContextMenu(marker) {
                        var contextMenu = new BMap.ContextMenu();
                        contextMenu.addItem(new BMap.MenuItem(("查看坐标"), function () {
                                alert("hello");
                        }));
                        marker.addContextMenu(contextMenu);
                }
        </script>
</body>
</html>

直接添加marker,然后给marker添加右键菜单,marker的右键菜单就能显示了。

如果我想通过右键菜单添加marker,再给marker添加右键菜单应该怎么做?

api 文档中没有写明吗??