Why is it working in JS but not C#

Hello all,

i have been trying to resize a boxcollider2d with code and it works with js but not with c# what am i doing wrong? i have the codes:

C#

 using UnityEngine;
 using System.Collections;
 
 public class gameSetup : MonoBehaviour {
 
     public Camera mainCam;
 
     public BoxCollider2D topWall;
 
 
 
     
     // Update is called once per frame
     void update () {
 
 
         topWall.size = new Vector2 (mainCam.ScreenToWorldPoint (new Vector3 (Screen.width * 2f, 0f, 0f)).x, 1f);
         topWall.center = new Vector2 (0f, mainCam.ScreenToWorldPoint (new Vector3 (0f, Screen.height, 0f)).y + 0.5f);
 
 
     
     }
 }

JS

 #pragma strict
 
 //Reference the camera
 var mainCam : Camera;
 
 //Reference the colliders we are going to adjust
 var topWall : BoxCollider2D;
 
 
 function Update () {
 
 
 
 
 
     //Move each wall to its edge location:
     topWall.size = new Vector2 (mainCam.ScreenToWorldPoint (new Vector3 (Screen.width * 2f, 0f, 0f)).x, 1f);
     topWall.center = new Vector2 (0f, mainCam.ScreenToWorldPoint (new Vector3 ( 0f, Screen.height, 0f)).y + 0.5f);
     
     
 
 }

And i have dragged camera and wall to the correct variables

Kind regards

Isak