Error: no name paramenter with name: 'trackCameraPosition: true' in flutter

[isofttechn]

When run flutter run -v, it works. But on flutter run, it display this error, The following _CompileTimeError was thrown building FireMap(dirty, state: FireMapState#0f0b0): I/flutter (13678): 'package:google_tracker/main.dart': error: lib/main.dart:39:9: Error: No named parameter with the I/flutter (13678): name 'trackCameraPosition'. I/flutter (13678): trackCameraPosition: true, I/flutter (13678): ^^^^^^^^^^^^^^^^^^^

Here is my main.dart:

import 'package:google_maps_flutter/google_maps_flutter.dart';

void main() => runApp(MyApp());
GoogleMapController mapController;

class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: FireMap(),
),
);
}
}

class FireMap extends StatefulWidget {
State createState() => FireMapState();
}

class FireMapState extends State {
GoogleMapController mapController;
build(context) {
return Stack(children: [
GoogleMap(
initialCameraPosition: CameraPosition(
target: LatLng(9.05785, 7.49508),
zoom: 15,

  ),

   onMapCreated: _onMapCreated,
    myLocationEnabled: true,
    mapType: MapType.hybrid,
    compassEnabled: true,
    trackCameraPosition: true, 

  ),

  Positioned(
    bottom: 50,
    right: 10,
    child:
    FlatButton(
    child: Icon(Icons.pin_drop, color: Colors.white),
    color: Colors.green,
    onPressed: () => _addMarker()  
    )
  )


]);
}

_onMapCreated(GoogleMapController controller) {
setState(() {
mapController = controller;
});
}
}

_addMarker() {
var marker = MarkerOptions(
position: mapController.cameraPosition.target,
icon: BitmapDescriptor.defaultMarker,
infoWindowText: InfoWindowText('Magic Marker', '🍄🍄🍄')
);

mapController.addMarker(marker);
}
How do i solve this, thanks