尝试在Unity中创建第三人称控制器，但玩家不移动

这是我目前所做的。

using UnityEngine;
using System.Collections;
public class PlayerMovement : MonoBehaviour {
    CharacterController control;
    [SerializeField]
    float moveSpeed = 5.0f;
    [SerializeField]
    float jumpSpeed = 20.0f;
    [SerializeField]
    float gravity = 1.0f;
    float yVelocity = 0.0f;
    // Use this for initialization
    void Start () {
        control = GetComponent<CharacterController> ();
    }
    // Update is called once per frame
    void Update () 
    {
        Vector3 direction = new Vector3 (Input.GetAxis ("Horizontal"), 0, Input.GetAxis ("Vertical"));
        Vector3 velocity = direction * moveSpeed;
        if (control.isGrounded) {
            if (Input.GetButtonDown ("Jump")) {
                yVelocity += jumpSpeed;
            }
        } else {
            yVelocity -= gravity;
        }
        velocity.y = yVelocity;
        control.Move (velocity*Time.deltaTime);
    }
}

我正在遵循教程，看起来一切都是一样的，但玩家没有移动。