Phaser: background image issue

Question

So, i have this problem, i'm doing that "flapy bird" game with Phaser, but when i put a background image moving, the other images (like the bird, pipes, and everything) won't display, and i don't know why, any ideas?, here's my code:

// Initialize Phaser, and creates a 400x490px game
var game = new Phaser.Game(400, 490, Phaser.AUTO, 'game_div');

// Creates a new 'main' state that wil contain the game
var main_state = {

    preload: function() { 
        // Change the background color of the game
        // this.game.stage.backgroundColor = '#71c5cf';


        // Load the bird sprite
        this.game.load.image('bird', 'assets/bird2.png');
        this.game.load.image('pipe', 'assets/pipe.png');
        this.game.load.audio('jump', 'assets/jump.wav');
        this.game.load.image("background", "assets/background.png");
    },

    create: function() { 
        // Display the bird on the screen
        this.bird = this.game.add.sprite(100, 245, 'bird');
        this.pipes = game.add.group();  
        this.pipes.createMultiple(20, 'pipe');
        this.timer = this.game.time.events.loop(1500, this.add_row_of_pipes, this);
        this.score = 0;  
        var style = { font: "30px Arial", fill: "#ffffff" };  
        this.label_score = this.game.add.text(20, 20, "0", style);
        this.jump_sound = this.game.add.audio('jump');
        this.bg= game.add.tileSprite(0, 0, game.stage.bounds.width, game.cache.getImage('background').height, 'background');

    // Add gravity to the bird to make it fall
    this.bird.body.gravity.y = 1000;  

    // Call the 'jump' function when the spacekey is hit
    var space_key = this.game.input.keyboard.addKey(Phaser.Keyboard.SPACEBAR);
    space_key.onDown.add(this.jump, this);
    this.bird.anchor.setTo(-0.2, 0.5); 
},

update: function() {

        // If the bird is out of the world (too high or too low), call the 'restart_game' function
        if (this.bird.inWorld == false)
            this.restart_game();
        this.game.physics.overlap(this.bird, this.pipes, this.restart_game, null, this);

        if (this.bird.angle < 20)  
            this.bird.angle += 1;

        this.game.physics.overlap(this.bird, this.pipes, this.hit_pipe, null, this);
        this.bg.tilePosition.x -= 1;
    },

// Make the bird jump 
jump: function() {
    this.jump_sound.play();
    if (this.bird.alive == false)  
    return; 
    // Add a vertical velocity to the bird
    this.bird.body.velocity.y = -350;

    // create an animation on the bird
    var animation = this.game.add.tween(this.bird);

    // Set the animation to change the angle of the sprite to -20° in 100 milliseconds
    animation.to({angle: -20}, 100);

    // And start the animation
    animation.start();
},

// Restart the game
restart_game: function() {  
    // Start the 'main' state, which restarts the game
    this.game.state.start('main');
    this.game.time.events.remove(this.timer);
},

add_one_pipe: function(x, y) {  
    // Get the first dead pipe of our group
    var pipe = this.pipes.getFirstDead();

    // Set the new position of the pipe
    pipe.reset(x, y);

    // Add velocity to the pipe to make it move left
    pipe.body.velocity.x = -200; 

    // Kill the pipe when it's no longer visible 
    pipe.outOfBoundsKill = true;
},

add_row_of_pipes: function() {  
    var hole = Math.floor(Math.random()*5)+1;

    for (var i = 0; i < 8; i++)
        if (i != hole && i != hole +1) 
            this.add_one_pipe(400, i*60+10);

        this.score += 1;  
        this.label_score.content = this.score;
    },

    hit_pipe: function() {  
    // Set the alive property of the bird to false
    this.bird.alive = false;

    // Prevent new pipes from appearing
    this.game.time.events.remove(this.timer);

    // Go through all the pipes, and stop their movement
    this.pipes.forEachAlive(function(p){
        p.body.velocity.x = 0;
    }, this);
},
};

// Add and start the 'main' state to start the game
game.state.add('main', main_state);  
game.state.start('main'); 

Answer 1

maybe try to add the background first in your create function.

create: function() {
     // Display background
     this.bg= this.game.add.tileSprite(0, 0, game.stage.bounds.width, game.cache.getImage('background').height, 'background');
     // Display the bird on the screen
     this.bird = this.game.add.sprite(100, 245, 'bird');

...
},

sometimes you use this.game and sometimes just game.