Gmaps.map.callback无法正常工作，无法在Gmaps4rails中添加侦听器

我的要求是在标记上添加onclik侦听器。我的看法如下

<div class="map-wrapper">
  <div id="map_div" style=" height: 800px;"></div>
</div>

<script src="//maps.google.com/maps/api/js?v=3.13&amp;sensor=false&amp;libraries=geometry" type="text/javascript"></script>
<script src='//google-maps-utility-library-v3.googlecode.com/svn/tags/markerclustererplus/2.0.14/src/markerclusterer_packed.js' type='text/javascript'></script>

<script>

handler = Gmaps.build('Google', { markers: { maxRandomDistance: null } });

var mapOptions = { mapTypeId: google.maps.MapTypeId.SATELLITE };
handler.buildMap({ provider: mapOptions,  internal: {id: 'map_div'}}, function(){
 markers = handler.addMarkers(<%=raw @hash.to_json %>);

 handler.bounds.extendWith(markers);
 handler.fitMapToBounds();
  handler.getMap().setZoom(19);

});



</script>
<% content_for :scripts do %>
<script type="text/javascript">
Gmaps.map.callback = function(){
  for(var i = 0; i < Gmaps.map.markers.length; i++){
    marker = Gmaps.map.markers[i];
    google.maps.event.addListener(marker.serviceObject, 'click',  (function(marker){return function(){alert(marker.id);}})(marker))
 }
}

</script>
<% end %>

但是当回调函数看起来没有被调用时。我在这里或布局application.html.erb中缺少什么吗？我在application.html.erb中放了

 <%= yield %>
<%= yield :scripts %>

我的控制器代码如下

 def index
    @sens = Sen.all
@hash = Gmaps4rails.build_markers(@sens) do |sen, marker|
marker.lat sen.latitude
marker.lng sen.longitude
marker.picture({"url" =>"/images/red_bl.gif","width" => 36, "height" => 36 })

结束logger.info @hash结束

rails版本是4.0.2 ruby​​ 1.9.3'gmaps4rails'，'2.1.1'