BCE0023: No appropriate version of 'UnityEngine.GUI.Button' for the argument list '(UnityEngine.Rect, int)' was found.

I am trying to switch camera when a button is pressed Here is my code

 var Main_Camera : Camera; 
 var Main_Camera_2 : Camera; 
 var Main_Camera_3 : Camera; 
 var Main_Camera_4 : Camera; 
 var Main_Camera_5 : Camera; 
 
 public var CameraView = 1; 
 public var Speed = 0;
 var updateInterval = 1.0;
 private var accum = 0.0; // FPS accumulated over the interval
 private var frames = 0; // Frames drawn over the interval
 private var timeleft : float; // Left time for current interval
 private var fps = 15.0; // Current FPS
 private var lastSample : double;
 private var gotIntervals = 0;
 
 function Start()
 {
  }
  
 function Update()
 {
 Speed = rigidbody.velocity.magnitude * 2.237;
 }
 
 function OnGUI()
 {
     GUI.Box(new Rect(Screen.width-160, 10, 150, 27), "Speed : " + Speed + ": MPH");
     
         if (GUI.Button(Rect(20,35,50,30), CameraView))    
     if(CameraView < 5) CameraView++;
     else CameraView = 1;
 }
  
 if( CameraView == 1){
     Main_Camera.enabled = true;
     Main_Camera_2.enabled = false;
     Main_Camera_3.enabled = false;
     Main_Camera_4.enabled = false;
     Main_Camera_5.enabled = false;
 } 
 else if ( CameraView == 2) {
     Main_Camera.enabled = false;
     Main_Camera_2.enabled = true;
     Main_Camera_3.enabled = false;
     Main_Camera_4.enabled = false;
     Main_Camera_5.enabled = false;
 } 
 else if ( CameraView == 3){
     Main_Camera.enabled = false;
     Main_Camera_2.enabled = false;
     Main_Camera_3.enabled = true;
     Main_Camera_4.enabled = false;
     Main_Camera_5.enabled = false;
 } 
 else if ( CameraView == 4){
     Main_Camera.enabled = false;
     Main_Camera_2.enabled = false;
     Main_Camera_3.enabled = false;
     Main_Camera_4.enabled = true;
     Main_Camera_5.enabled = false;
 } 
 else if ( CameraView == 5){
     Main_Camera.enabled = false;
     Main_Camera_2.enabled = false;
     Main_Camera_3.enabled = false;
     Main_Camera_4.enabled = false;
     Main_Camera_5.enabled = true;
 }

(dont mind some of the variables theyre there for something else)

I have attached the cameras and everything and it should working but when I try to get the button to display Camera View variable I get "BCE0023: No appropriate version of 'UnityEngine.GUI.Button' for the argument list '(UnityEngine.Rect, int)' was found."

Its probably something simple but if anyone knows what the problem is please answer Thank you