google-map-marker is not shown

[HugoMarteau]

I'm displaying the map with google-map correctly but when I want to create a marker inside, it is simply not taken in consideration.

Even if I change the coordinates of the marker and add fit-to-marker to the google-map , the map is still showing me the default position (San fransisco) without the marker.

[HugoMarteau]

Update
I acheived to display the markers just adding

  <script>
    window.Polymer = {
      dom: 'shadow'
    };
  </script>

in the head of index.html

[Christopher Beam]

The attribute is also called fit-to-markers