Unity找不到其他GameObject的脚本

我从另一个GameObject的脚本中获取变量时遇到问题。。我以前使用过这种类型的引用，我知道它是如何工作的，但出于某种原因，它说它找不到我引用的脚本。

引用其他代码的代码（如果CanHearPlayer（）开头的语句）：

using UnityEngine;
using System.Collections;
public class EnemySight : MonoBehaviour {
public GameObject Player;
public float fieldOfViewDegrees = 30;
public float visibilityDistance = 50;
public bool SeeingPlayer;
public float deathDistance;
public float hearDistance;
void Update(){
    SeeingPlayer = CanSeePlayer();
    float Distance = Vector3.Distance(transform.position, Player.transform.position);
    if ((SeeingPlayer == true)) {
        transform.LookAt(Player.transform.position);
        if (Distance < deathDistance){
            Debug.Log("You died");
            //Game over sequence starts here
        }
    }
    if (CanHearPlayer () == true) {
        Debug.Log ("I can hear you.");
    }
}
protected bool CanSeePlayer()
{
    RaycastHit hit;
    Vector3 rayDirection = Player.transform.position - transform.position;
    if ((Vector3.Angle(rayDirection, transform.forward)) <= fieldOfViewDegrees * 0.5f)
    {
        // Detect if player is within the field of view
        if (Physics.Raycast(transform.position, rayDirection, out hit, visibilityDistance))
        {
            return (hit.transform.CompareTag("Player"));
        }
    }
    return false;
}
protected bool CanHearPlayer(){
    RaycastHit hit;
    Vector3 rayDirection = Player.transform.position - transform.position;
    if (Player.GetComponent<FirstPersonController>().MakingWalkingSound == true) {
        hearDistance = 50;
    } else {
        hearDistance =  5;
    }
    if (Player.GetComponent<FirstPersonController>().MakingRunningSound == true) {
        hearDistance = 100;
    }
    if (Physics.Raycast(transform.position, rayDirection, out hit, hearDistance))
    {
        return (hit.transform.CompareTag("Player"));
    }
    return false;
}

}

公共游戏对象"玩家"在Unity中被定义为包含"FirstPersonController"脚本作为组件的对象。

它所指的代码（部分代码）：

public class FirstPersonController : MonoBehaviour
{
    public bool MakingWalkingSound;
    public bool MakingRunningSound;
private void GetInput(out float speed)
{
     // Read input
    float horizontal = CrossPlatformInputManager.GetAxis("Horizontal");
    float vertical = CrossPlatformInputManager.GetAxis("Vertical");
    MakingWalkingSound = !(horizontal == 0 && vertical == 0);
    MakingRunningSound = Input.GetKey(KeyCode.LeftShift);
}

错误为：Assets/EnemySight.cs（53,41）：error CS0246:找不到类型或命名空间名称"FirstPersonController"。是否缺少using指令或程序集引用？And：Assets/EnemySight.cs（59,41）：error CS0246:找不到类型或命名空间名称"FirstPersonController"。是否缺少using指令或程序集引用？

这些行对应于CanHearPlayer中的前两个if语句。

我做错了什么？我在谷歌和StackOverflow上搜索过，但找不到问题出在哪里。

谢谢！

namespace MyNamespace.Blah { 
    public class FirstPersonController : MonoBehaviour {
        ...
    }
}

using MyNamespace.Blah;
public class EnemySight : MonoBehaviour {
    ...
}