The Hero widget doesn't launch the first time (Flutter) - flutter

Question

The animation doesn't work the first time it's launched (onTap in GestureDetector), but it works the next time if I go backwards. And I don't know why.
Here is my code :
in main.dart :
import 'package:fairlove/screen/splash_screen.dart';
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: SplashScreen(),
);
}
}
splash_screen and login_screen are under the 'screen' folder.
in screen/splash_screen.dart :
import 'package:flutter/material.dart';
import 'login_screen.dart';
class SplashScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
body: Hero(
tag: 'homeLogo',
child: GestureDetector(
onTap: () => Navigator.push(context, MaterialPageRoute(builder: (context) => LoginScreen(),)),
child: Image.asset('assets/logo.png')
),
),
);
}
}
when I click on the image the first time, it goes to LoginScreen, ok, but without animation.
and in in screen/login_screen.dart :
import 'package:flutter/material.dart';
const users = const {
'a#a.a': 'aaa',
'hunter#gmail.com': 'hunter',
};
class LoginScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
final userNameController = TextEditingController();
final passwordController = TextEditingController();
final logo = Hero(
tag: 'homeLogo',
child: CircleAvatar(
backgroundColor: Colors.transparent,
radius: 40.0,
child: Image.asset('assets/logo.png'),
));
final txtUserName = TextField(
controller: userNameController,
decoration: InputDecoration(
hintText: 'Username',
contentPadding: EdgeInsets.fromLTRB(20.0, 10.0, 20.0, 10.0),
border: OutlineInputBorder(borderRadius: BorderRadius.circular(30.0))
),
);
final txtPassword = TextField(
controller: passwordController,
obscureText: true,
decoration: InputDecoration(
hintText: 'Password',
contentPadding: EdgeInsets.fromLTRB(20.0, 10.0, 20.0, 10.0),
border: OutlineInputBorder(borderRadius: BorderRadius.circular(30.0))
),
);
final btnLogin = RaisedButton(
color: Colors.deepPurpleAccent,
textColor: Colors.white,
shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(10.0))),
onPressed: () {
if(userNameController != null && userNameController.text == "abc"
&& passwordController!= null && passwordController.text == "123") {
//Navigator.of(context).pushReplacement(newRoute)
}
},
child: Text('Login', style: TextStyle(fontSize: 20.0),),
);
final btnForgetPassword = FlatButton(
onPressed: () { },
child: Text('Forget Password', style: TextStyle(color: Colors.blue),),
);
return Scaffold(
body: Center(
child: Container(
width: 400,
height: 400,
child: ListView(
padding: EdgeInsets.only(left: 25.0, right: 25.0),
children: <Widget>[
logo,
SizedBox(height: 20.0),
txtUserName,
SizedBox(height: 20.0),
txtPassword,
SizedBox(height: 20.0),
btnLogin,
btnForgetPassword
],
),
),
),
);
}
}
If I go back or/and click again the image on the previous screen, Hero animation works.