新手求教：NullReferenceException

报错的原因就是你代码不正确，咋么会完全正正确~

var obj : GameObject;
var speed:int=100;
function Start()
{obj = GameObject.Find("Cylinder");}//获得立方体对象
function OnGUI()
{if(GUILayout.Button("开始克隆实例",GUILayout.Height(50)))
{var clone :GameObject = Instantiate(obj,obj.transform.position, obj.transform.rotation);}
if(GUILayout.Button("立即销毁模型",GUILayout.Height(50)))
{Destroy (obj);}
if (GUILayout.Button("向前移动",GUILayout.Height(50)))
{obj.transform.Translate (Vector3.forward * Time.deltaTime);}
if(GUILayout.Button("向后移动",GUILayout.Height(50)))
{obj.transform.Translate(Vector3.fwd * Time.deltaTime);}
if(GUILayout.Button("向左移动",GUILayout.Height(50)))
{obj.transform.Translate(Vector3.left * Time.deltaTime);}
if(GUILayout.Button("向右移动",GUILayout.Height(50)))
{obj.transform.Translate(Vector3.right * Time.deltaTime);}
if(GUILayout.Button("沿X轴旋转",GUILayout.Height(50)))
{obj.transform.Rotate(Vector3.right * Time.deltaTime*speed);}
if(GUILayout.Button("沿Y轴旋转",GUILayout.Height(50)))
{obj.transform.Rotate(Vector3.up * Time.deltaTime*speed);}
if(GUILayout.Button("沿Z轴旋转",GUILayout.Height(50)))
{obj.transform.Rotate(Vector3.forward * Time.deltaTime*speed);}
//GUILayout.Label("立方体的位置："+obj.transform.position);
}
补上代码
拷贝一下同学的没问题的代码，也出错，拷贝了整个文件，在我计算机上能运行······