How to display map using geocode

My Script is

<script type="text/javascript">
 var lat = <%= @town.latitude %>, 
 lon = <%= @town.longitude %>,
 map;
function initialize() {
  var myOptions = {
  center: new google.maps.LatLng(lat, lon)
};
   map = new google.maps.Map(document.getElementById('map_canvas'),
    myOptions);
}
 google.maps.event.addDomListener(window, 'load', initialize);

  <script type="text/javascript" src="//maps.google.com/maps?file=api&  v=2.x&key="My api key"&libraries=places"></script>

I can fetch latitude and longitude but my map is not loading.Could anyone help me with this?