Background Location - Flutter

I have developed an application in flutter to capture the coordinates. code below is capturing coordinates correctly but the problem is, it is not working when the application is closed. I need to capture the location even the app is closed.Any help will be appreciated

@override
void initState() 
{
 super.initState( );
 BackgroundLocation.startLocationService( );
 BackgroundLocation.getLocationUpdates( (location) async {
  setState( () {
    debugPrint(globals.sUserCode);
    debugPrint(globals.sActiveTripCode);
    this.latitude = location.latitude.toString( );
    this.longitude = location.longitude.toString( );
    this.accuracy = location.accuracy.toString( );
    this.altitude = location.altitude.toString( );
    this.bearing = location.bearing.toString( );
    this.speed = location.speed.toString( );
    this.time =
        DateTime.fromMillisecondsSinceEpoch( location.time.toInt( ) )
            .toString( );
  } );
 }