Please help get my code to work...compiler errors

New to unity and I cannot for the life of me figure out what the problem is in this code. I'm working from a book (Unity in Action) and even after what I thought was copying line for line, I still get errors.

 using UnityEngine;
 using System.Collections;
 public class RayShooter : MonoBehaviour {
     private Camera _camera;
     void Start() {
         _camera = GetComponent<Camera>();
         Cursor.lockState = CursorLockMode.Locked;
         Cursor.visible = false;
     }
     void OnGUI() {
         int size = 12;
         float posX = _camera.pixelWidth/2 - size/4;
         float posY = _camera.pixelHeight/2 - size/2;
         GUI.Label(new Rect(posX, posY, size, size), "*");
     }
     void Update() {
         if (Input.GetMouseButtonDown(0)) {
             Vector3 point = new Vector3(_camera.pixelWidth/2, _camera.pixelHeight/2, 0);
             Ray ray = _camera.ScreenPointToRay(point);
             RaycastHit hit;
             if (Physics.Raycast(ray, out hit)) {
                 GameObject hitObject = hit.transform.gameObject;
                 ReactiveTarget target = hitObject.GetComponent<ReactiveTarget>();
                 if (target != null) {
                     target.ReactToHit();
                 } else {
                     StartCoroutine(SphereIndicator(hit.point));
                 }
             }
         }
         private IEnumerator SphereIndicator(Vector3 pos) {
             GameObject sphere = GameObject.CreatePrimitive(PrimitiveType.Sphere);
             sphere.transform.position = pos;
             yield return new WaitForSeconds(1);
             Destroy(sphere);
         }
     }

Apparently there is an error with 'private' being unexpected and a '(' somewhere. Please help, I've been at this forever...