求大神, Unity的问题

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[System.Serializable]
public class Boundary{
public float xMin, xMax, zMin, zMax;
}
public class PlayerController : MonoBehaviour {
public float speed;
public Boundary boundary = new Boundary();

void FixedUpdate(){
    float moveHorizontal = Input.GetAxis ("Horizontal");
    float moveVertical = Input.GetAxis ("Vertical");

    Vector3 movement = new Vector3 (moveHorizontal, 0.0f, moveVertical);
    this.GetComponent<Rigidbody> ().velocity = movement * speed;
    this.GetComponent<Rigidbody> ().position = new Vector3 (
        Mathf.Clamp(this.GetComponent<Rigidbody>().position.x, boundary.xMin, boundary.xMax),
        0.0f,
        Mathf.Clamp(this.GetComponent<Rigidbody>().position.z, boundary.zMin, boundary.zMax)
    );
}

}
为什么在层级面板中不显示Boundary 不是应该显示的吗

代码没问题,也能够显示出来。
注意编辑完代码后,**保存代码,并在Inspector面板中点击该脚本三角符号”

图片说明

http://tieba.baidu.com/p/4490847520