Problem with an extended Phaser.Physics.Arcade.Sprite

[Genkics]

Hello I'm a beginner with Phaser and I want to extended a physcis sprite.

So this is my code.

class Player extends Phaser.Physics.Arcade.Sprite {

    constructor (scene, x, y,texture)
    {
        super(scene, x, y,texture);
    }
}
var player1;
var MyScene = new Phaser.Class({

    Extends: Phaser.Scene,

    initialize:

    function MyScene (config)
    {
        Phaser.Scene.call(this, config)
    },

    preload: function ()
    {
      this.load.image('back', 'img/background.jpg');
	  this.load.image('dude', 'img/player.png');
    },

    create: function ()
    {
    this.add.image(540,360, 'back');
	player1 = new Player(this, 400, 100, 'dude');
	this.add.existing(player1);
    }

});


				 var config = {
	type: Phaser.AUTO,
	width: 1080,
	height: 720,
	physics: {
		default: 'arcade',
		arcade: {
			gravity: { y: 1000 },
			debug: false
		}
	},
	scene: MyScene	
};
var game = new Phaser.Game(config);

The object display the sprite but the object don't fall and I can not set something in my class.

I search a long time a long time on internet and I didn't found. 

Do someone know where is my mistake  ?