Switch Case for Basic AI....

Here's the problem, I'm trying to make the AI react to the player's mouse. By clicking the AI, we will call Bob, you can have Bob randomly change his direction. The problem is that when I try to click Bob, he doesn't move anywhere other then the default direction.

The Code:

 var speed = 5;
 var deer = 10;
 var tap = 100;
 var rotate;
 
 function Update () {
     transform.position += transform.forward * Time.deltaTime * speed;
 }    
 
 function OnMouseEnter() {
     speed = 15;
     TotalScoreScript.Points += deer + 10;
 }
 
 function OnMouseExit () {
     speed = 5;
 }
 
 function OnMouseDown () {
     TotalScoreScript.Points += tap + 100;
 }
     
 function ChangeDirection() {
     dir = Random.Range(2,-2);
 
     switch(dir){
         case -2:
             rotate = -135;
         break;
         
         case -1:
             rotate = -45;
         break;
         
         case 1:
             rotate = 45;
         break;
         
         case 2:
             rotate = 135;
         break;
         
         default:
             rotate = 0;
         break;
         }
         
     if(rotate!=0){
         transform.Rotate(Vector3.up, rotate);
     }
 }