Frog won't turn

private Animator playerAnimator;
private float moveHorizantal;
private float moveVertical;
private Vector3 movement;
private float turningspeed = 20f;
private Rigidbody playerRigidbody;
private float turningSpeed;

// Use this for initialization
void Start () {
    // Gather Components from the Player GameObject
    playerAnimator = GetComponent<Animator> ();
    playerRigidbody = GetComponent<Rigidbody> ();

}

// Update is called once per frame
void Update () {

    // Gather Input from the Keyboard
    moveHorizantal = Input.GetAxisRaw ("Horizontal");
    moveVertical = Input.GetAxisRaw ("Vertical");

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

}

void FixedUpdate () {

    // If the Player's Movement Vector does not Equal Zero... 
    if (movement != Vector3.zero) {

        // ...then create a target rotation based on the movement vector...
        Quaternion targetRotation = Quaternion.LookRotation(movement, Vector3.up);

        //...and create another rotation that moves from the current rotation to the target rotation...
        Quaternion newRotation = Quaternion.Lerp (playerRigidbody.rotation, targetRotation, turningSpeed * Time.deltaTime);

        //...and change the players rotation to the new incremental rotation
        playerRigidbody.MoveRotation(newRotation);  

        //...then play the jump animation
        playerAnimator.SetFloat ("Speed", 3f);
    } else {
        // otherwise dont play the jump animation
        playerAnimator.SetFloat ("Speed", 0f);

    }
}