marker link to a post?

I am trying to use the below code as i got it from many results on google search:

GeoMashup.addAction( 'selectedMarker', function( properties, marker ) {
  var loc = GeoMashup.locations[ marker.getPoint() ];
  if ( loc && loc.objects.length > 0 ) {
    parent.location.href = properties.home_url + '?p=' + loc.objects[0].object_id;
  }
} );

I placed that above code within <script>...</script> in my footer and Wp is loading its own jQuery from header as normal.

But I get this error in consolle and when I click nothing happens, settings in the plugin are set not to open info box etc. Error i get:

Uncaught ReferenceError: GeoMashup is not defined

What Am I doing wrong?

Thanks

https://wordpress.org/plugins/geo-mashup/