libgdx - Texture not appearing sometimes

Question

When I run the App the Ball moves sometimes downwards, but sometimes its not moving. I dont change anything on script.

What I want is the ball should come from top outside of the screen, but when its visible in screen it should get an random xSpeed.

To test it I added first the bomb in the middle of the screen. But as I said the Ball is not showing sometimes. I run the game on my samsung galaxy s6 edge and the ball is there. Then when I run again it's not there.

That's how I coded.

private static final int SPRITE_SIZE = 32; // It has 32px width and height
private static final int SPRITE_COUNT = 4; // there are 4 sprites
private static final float MAX_SPEED = 1f; // maxspeed
private static final float MIN_SPEED = 0.25f; // min speed

private Vector2 position;
private Animation anim;
private Random random;

private float speedX, speedY;

public Bomb() {
    random = new Random();
    int rand = random.nextInt(2);

    TextureRegion tmp = new TextureRegion(Asset.sprites, SPRITE_SIZE * SPRITE_COUNT, rand * SPRITE_SIZE);
    anim = new Animation(tmp, SPRITE_COUNT, 0.75f);

    position = new Vector2((MainGame.WIDTH/2) - (SPRITE_SIZE/2), MainGame.HEIGHT);
    speedX = 0;
    speedY = -MAX_SPEED;
}

public void update(float dt) {
    anim.update(dt);
    if(speedX == 0) {
        if(position.y + SPRITE_SIZE < MainGame.HEIGHT) {
            speedX = random.nextFloat() * (MAX_SPEED - MIN_SPEED) + MIN_SPEED;
    }
    position.add(speedX, speedY);
}

public void render(SpriteBatch sb) {
    sb.begin();
    sb.draw(anim.getFrame(), position.x, position.y);
    sb.end();
}

EDIT: Maybe here's a problem?

Asset.java

public class Asset {
    public static Texture sprites;

    public static void init() {
        sprites = new Texture(Gdx.files.internal("sprite.png"));
    }

    public static void dispose() {
        sprites.dispose();
    }
}

Animation.java

public class Animation {
    private Array<TextureRegion> frames;
    private float maxFrameTime;
    private float currentFrameTime;
    private int frameCount;
    private int frame;

    public Animation(TextureRegion region, int frameCount, float cycleTime) {
        frames = new Array<TextureRegion>();
        int frameWidth = region.getRegionWidth() / frameCount;
        for(int i = 0; i < frameCount; i++) {
            frames.add(new TextureRegion(region, i * frameWidth, 0, frameWidth, region.getRegionHeight()));
        }
        this.frameCount = frameCount;
        maxFrameTime = cycleTime / frameCount;
        frame = 0;
    }

    public void update(float dt) {
        currentFrameTime += dt;
        if(currentFrameTime > maxFrameTime) {
            frame++;
            currentFrameTime = 0;
        }
        if(frame >= frameCount) {
            frame = 0;
        }
    }

    public TextureRegion getFrame() {
        return frames.get(frame);
    }

    public void dispose() {
        for (int i = 0; i < frames.size; i++) {
            frames.get(i).getTexture().dispose();
        }
    }
}

Answer 1

The problem was in this line.

TextureRegion tmp = new TextureRegion(Asset.sprites, SPRITE_SIZE * SPRITE_COUNT, rand * SPRITE_SIZE);

I've used the wrong params, so I forgot width and height.

I changed to this.

TextureRegion tmp = new TextureRegion(Asset.sprites, 0, rand * SPRITE_SIZE, SPRITE_SIZE*SPRITE_COUNT, SPRITE_SIZE);