Frog does not move with arrow keys

private Animator playerAnimator;
private float moveHorizontal;
private float moveVertical;
private Vector3 movement;

// Use this for initialization
void Start () {
    playerAnimator = GetComponent<Animator> (); 
}

// Update is called once per frame
void Update () {
    moveHorizontal = Input.GetAxisRaw ("Horizontal");
    moveVertical = Input.GetAxisRaw ("Vertical");

    movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);

}

void fixedUpdate () {
    if (movement != Vector3.zero)
    {
        playerAnimator.SetFloat("Speed", 3f);
    } else {
        playerAnimator.SetFloat("Speed", 0f);
    }

}