在完成Roll A Ball案例时，运行小球进行移动时，出现黄色图标警告，在此行为上的索引脚本丢失 

以下是unity出现错误的

The referenced script on this Behaviour is missing!
The referenced script on this Behaviour (Game Object 'Player') is missing!

 以下是VS中代码组成

public class Player : MonoBehaviour {
    private Rigidbody rd;
    public int force = 5;
	// Use this for initialization
	void Start () {
        rd = GetComponent<Rigidbody>();  //使得rd指向刚体组件

	}
	
	// Update is called once per frame
	void Update () {
        float h = Input.GetAxis("Horizontal");
        float v = Input.GetAxis("Vertical");
        rd.AddForce(new Vector3(h, 0, v) * force); 
	}

看了半天没搞明白究竟是哪里的问题，游戏能正常运行，就是一运行控制台就会出现黄色警告图标

版本号unity20171.1.p4    vs2013