Array of buttons not displaying in game

I am trying to take an array of images and display them in buttons. Depending on the size of the array, it is suppose to create a button per image. The problem is that when i try to run the code I get this error:

NullReferenceException: Object reference not set to an instance of an object
Boo.Lang.Runtime.RuntimeServices.InvokeBinaryOperator (System.String operatorName, System.Object lhs, System.Object rhs)
NewBehaviourScript.DrawButtons () (at Assets/NewBehaviourScript.js:13)
NewBehaviourScript.Update () (at Assets/NewBehaviourScript.js:8)

My question is what am I doing wrong?
this is the code:

 var numberOfButtonsWide = 6;
   var topLeft = Vector2(100,100);
   var width = 800;
   var buttonHeight = 60;
 var myList : Texture[];

  function Start(){
  DrawButtons();
  }
   function DrawButtons()
   {
     var buttonWidth = width/numberOfButtonsWide;
      for(var x =0; x < myList.Count; x++)
 
      {
           if(GUI.Button(
                Rect(topLeft.x + (x % numberOfButtonsWide) * buttonWidth, 
                       topLeft.y + Mathf.FloorToInt(x / numberOfButtonsWide) * buttonHeight,buttonWidth,buttonHeight),
                 GUIContent (myList[x])))
           {
          
           }
      }
   }

GUI method use only into OnGUI() function. And use Texture2D instead of Texture:

 function Start(){
 
 }

 function OnGUI(){
  DrawButtons();
 }

I hope that it will help you.