Google maps kml layer

Question

Hi, my code is:

var ctaLayer = new google.maps.KmlLayer(
    'http://.../per1.kml',
     {suppressInfoWindows: true});
ctaLayer.setMap(map);


 var info_percurso = new google.maps.InfoWindow({
  content: 'hi'
 });

  google.maps.event.addListener(ctaLayer, 'click', function() {

  info_percurso.open(map,ctaLayer);

  alert("dd");
}); 

this is possible? this code doesn't work...but the operation is possible?

I need to create my own infoWindow for database queries