How to create a random array avoiding repeat same value

Hi guys,

I have created an array which displays random instructions but I don't want that the instructions will repeat once have been displayed. Using the code below the instructions are not displayed. Any ideas why?

Thanks in advance for your help.

 static var randomInstruction:int;
 static var randomVariable:String;
 
 private var showingObject : boolean = true;
 
 static var objectToBeFound:int;
 
 static var GeneratedNumbers :int[];
 
 static var objectsInstructions = new String [3];
 
 
 objectsInstructions [0] = "keys";
 objectsInstructions [1] = "sun";
 objectsInstructions [2] = "star";
 objectsInstructions [3] = "pencil";
 
 
 static function GenerateNumbers ():int 
 {  
         randomInstruction = Random.Range (0,objectsInstructions.Length);
         while (GeneratedNumbers[randomInstruction] == randomInstruction)
             {
             randomInstruction = Random.Range (0,objectsInstructions.Length);
             }
         GeneratedNumbers[randomInstruction] = randomInstruction; 
         return randomInstruction;
 }
 
 function Start ()
 {
     
     
     randomInstruction = GenerateNumbers();
     randomVariable = objectsInstructions[randomInstruction];  
     nrOfObjects = nrOfObjects++;
     
     objectToBeFound = randomInstruction;
     
     yield new WaitForSeconds (5);    
     yield WaitForSeconds(9);
     showingObject = false;
     
     GeneratedNumbers= new int[3];
     for (var i = 0; i < GeneratedNumbers.Length; i++) 
     {
         GeneratedNumbers[i]=-1;
     }
 }
 
 
 function OnGUI ()
 {
     GUI.skin=customSkin;
 
     if(showingObject)
         {    
         GUI.Box(Rect(75, 650, 900, 80), randomVariable);
         }
 }