Strategy camera problems.

HI! i am trying to make a strategy space game and so i thought that i would start with the basic things like camera and main menu first. i have found a good RTS camera view with full controls but i am having problems when trying to use it, some errors pop up and i don't know why, i have tryed to fix it but im not the best with coding yet and so i am finding it hard :/

I NEED HELP! Heres the code:

using UnityEngine;

public class MouseRts : MonoBehaviour { public int LevelArea = 100;

 public int ScrollArea = 25;
 public int ScrollSpeed = 25;
 public int DragSpeed = 100;

 public int ZoomSpeed = 25;
 public int ZoomMin = 20;
 public int ZoomMax = 100;

 public int PanSpeed = 50;
 public int PanAngleMin = 25;
 public int PanAngleMax = 80;

 // Update is called once per frame
 void Update()
 {
     // Init camera translation for this frame.
     var translation = Vector3.zero;

     // Zoom in or out
     var zoomDelta = Input.GetAxis("Mouse ScrollWheel")*ZoomSpeed*Time.deltaTime;
     if (zoomDelta!=0)
     {
         translation -= Vector3.up * ZoomSpeed * zoomDelta;
     }

     // Start panning camera if zooming in close to the ground or if just zooming out.
     var pan = camera.transform.eulerAngles.x - zoomDelta * PanSpeed;
     pan = Mathf.Clamp(pan, PanAngleMin, PanAngleMax);
     if (zoomDelta < 0 || camera.transform.position.y < (ZoomMax / 2))
     {
         camera.transform.eulerAngles = new Vector3(pan, 0, 0);
     }

     // Move camera with arrow keys
     translation += new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));

     // Move camera with mouse
     if (Input.GetMouseButton(2)) // MMB
     {
         // Hold button and drag camera around
         translation -= new Vector3(Input.GetAxis("Mouse X") * DragSpeed * Time.deltaTime, 0, 
                            Input.GetAxis("Mouse Y") * DragSpeed * Time.deltaTime);
     }
     else
     {
         // Move camera if mouse pointer reaches screen borders
         if (Input.mousePosition.x < ScrollArea)
         {
             translation += Vector3.right * -ScrollSpeed * Time.deltaTime;
         }

         if (Input.mousePosition.x >= Screen.width - ScrollArea)
         {
             translation += Vector3.right * ScrollSpeed * Time.deltaTime;
         }

         if (Input.mousePosition.y < ScrollArea)
         {
             translation += Vector3.forward * -ScrollSpeed * Time.deltaTime;
         }

         if (Input.mousePosition.y > Screen.height - ScrollArea)
         {
             translation += Vector3.forward * ScrollSpeed * Time.deltaTime;
         }
     }

     // Keep camera within level and zoom area
     var desiredPosition = camera.transform.position + translation;
     if (desiredPosition.x < -LevelArea || LevelArea < desiredPosition.x)
     {
         translation.x = 0;
     }
     if (desiredPosition.y < ZoomMin || ZoomMax < desiredPosition.y)
     {
         translation.y = 0;
     }
     if (desiredPosition.z < -LevelArea || LevelArea < desiredPosition.z)
     {
         translation.z = 0;
     }

     // Finally move camera parallel to world axis
     camera.transform.position += translation;
 }

}

Please help :/