C# 无法使用GUI.Button移动播放机

我正在创建一个简单的游戏，现在我要移动我的玩家。我想用手机上的四个触摸按钮移动我的播放器。我正在使用GuitTexture按钮并使用下面的代码。但是，我遇到了以下错误：

与UnityEngine.GUI.ButtonUnityEngine.Rect的最佳重载方法匹配的字符串具有一些无效参数

如何修复它

代码

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若你们想在按钮上显示文字，那个么只需在左、下、上、右引号中加上。如果您想要带有图像的按钮，请将GuitTexture类型更改为纹理或纹理2D，如此处所述-

左、右、上、下不是字符串，它们被声明为GuitTexture如何解决此问题？请更正我的密码好吗？

public class Player : MonoBehaviour {
    public float movement;
    public Vector3 input;
    private float maxSpeed=15f;
    private Vector3 spawn;
    public GameObject deathparticales;
    public GUITexture Left;
    public GUITexture Right;
    public GUITexture Up;
    public GUITexture Down;
    private bool moveRight, moveLeft, moveUp, moveDown;

    // Use this for initialization       
    void Start () {
        spawn = transform.position;
    }

    // Update is called once per frame
    void Update () {
        if (GUI.Button(Rect (50,50,50,50), Left))
        {
            Vector3 position = this.transform.position;
            position.x--;
            this.transform.position = position;
        }

        if (GUI.Button(Rect (100,50,50,50), Right))
        {
            Vector3 position = this.transform.position;
            position.x++;
            this.transform.position = position;
        }

        if (GUI.Button(Rect (75,100,50,50), Up))
            {
            Vector3 position = this.transform.position;
            position.y++;
            this.transform.position = position;
        }

        if (GUI.Button(Rect (25,100,50,50), Down))
        {
            Vector3 position = this.transform.position;
            position.y--;
            this.transform.position = position;
        }

        if (transform.position.y < -1) {
            Die ();
        }
    }

    void OnCollisionEnter(Collision death)
    {
        if(death.transform.tag == "Enemycollision")
        {
            Die();

        }
    }

    void OnTriggerEnter(Collider target)
    {
        if (target.transform.tag == "Target") {
        Gamemanager.completelevel();
        }
    }

    void Die()
    {
        Instantiate(deathparticales,transform.position,Quaternion.Euler(270,0,0));
        transform.position=spawn;
    }
}