Weird error, please help!

I attached this script on an object so it rotates towards cursor but it says the following error:

Script:

Code (csharp):

1. function Update() {
2.     if(networkView.isMine) {
3.     var playerPlane = new Plane(Vector3.up, transform.position);
4.    
5.     var ray = Camera.main.ScreenPointToRay (Input.mousePosition);
6.    
7.    
8.     var hitdist = 0.0;
9.     if (playerPlane.Raycast (ray, hitdist)) {
10.    
11.         var targetPoint = ray.GetPoint(hitdist);
12.        
13.         var targetRotation = Quaternion.LookRotation(targetPoint - transform.position);
14.        
15.         transform.rotation = targetRotation;
16.         }
17.     }
18. }

Error:

NullReferenceException
UnityEngine.Camera.ScreenPointToRay (Vector3 position) (at C:/BuildAgent/work/812c4f5049264fad/Runtime/ExportGenerated/Editor/UnityEngineCamera.cs:291)
Rotate.Update () (at Assets/Cubes/Rotate.js:5)

Please help me! Thank you very much!

 

Do you have any camera tagget as "MainCamera"?

http://docs.unity3d.com/Documentation/ScriptReference/Camera-main.html

 

Thanks man, MainCamera tag was missing on a camera.