Marker cannot be plotted in the google map

Ionic Framework ionic-v3
1

My code

 getdata() {
  this.httpProvider.getJsonData().subscribe(data => {
    this.addMarkersToMap(data);
   // console.log("mmm",data);
  });
}

  addMarkersToMap(markers) {
   
    console.log("inside data",markers);
    for (let marker of markers) {
       console.log(marker);
      let position = new google.maps.LatLng(marker.latitude, marker.longitude);
      console.log("pp",position);
      var dogwalkMarker = new google.maps.Marker({ position: position });
      dogwalkMarker.setMap(this.maps.map);
     
    } 
  }

Marker cannot be showed in the google map, anything as i m missing?

Thanks…