Ionic native google maps: maps can't loaded

Hi,

i had a problem when i load the maps. i have tried to print the “mapOptions” and “this.map” on console and there are no error, but the map still can’t loaded.

anyone can help me?

this is my code :
loadMap() {
let mapOptions: GoogleMapOptions = {
camera: {
target: {
lat: this.lat,
lng: this.lng
},
zoom: 16,
tilt: 30
}
};

this.map = GoogleMaps.create('map_canvas', mapOptions);

console.log(mapOptions);
console.log(this.map);

this.marker = this.map.addMarkerSync({
  title: this.member_name,
  icon: 'red',
  animation: 'BOUNCE',
  position: {
	lat: this.lat,
	lng: this.lng
  }
});
this.marker.on(GoogleMapsEvent.MARKER_CLICK).subscribe(() => {
  //alert('clicked');
});

}

and this is the problem :