UnityScript set button text

I am trying to set the text of a button programmatically that I made in UnityScript. This is way harded than it should be.

Here is my UnityScript code:

 #pragma strict
 
 var loginButton : UnityEngine.UI.Button;
 
 function Start () {
 
     var canvas = new GameObject ("canvas", Canvas);
 
     var instance : UnityEngine.UI.Button = Instantiate(loginButton);
     
     instance.GetComponent<GUIText>().text = "login"; // doesnt work
     
     
     instance.transform.position = Vector2(0,0);
     instance.transform.SetParent(canvas.transform);
 
 }