Main Menu scrpit not working

I'm trying to script my main menu for my game Here is the script

using UnityEngine; using System.Collections;

//extend MonoBehaviour so that we can attach this script to an object public class MenuObject: MonoBehaviour { //A public bool so that we can change in the editor whether or not the button will quit the application public bool isQuit = false;

     //For the next three functions, the collider is absolutely necessary
     //these functions will not fire off if there is no collider


     //Fires off when the mouse hovers over the collider
     //When the mouse is over the item, change the colour of it to 
     //red so that the player knows that it is interacting with it
     void OnMouseEnter()
      {
              renderer.material.color = Color.red;
      }
 
     //Fires off when the mouse leaves the object
     //We want to change the colour of the object back to it's original when the mouse 
     //is no longer over it so that is exactly what we do here
     void OnMouseExit()
      {
              renderer.material.color = Color.white;
      }



     //Fires off when the mouse is clicked while hovering over the object
     //Here we check if the bool was set to true or not and we load the level id not
     //or quit the application if true
     void OnMouseDown()
      {
             if(isQuit)
              {
                     Application.Quit();
              }
             else
              {
                     Application.LoadLevel(1);
              }
      }

}

}