Can't draw a box using Basic GUI

Very... VERY... Basic script... I mean... Come on..

 using UnityEngine;
 using System.Collections;
 
 public class StatPoints : MonoBehaviour {
     void OnGUI() {
          GUI.Box(new Rect(10, 20, 20, 20), "hi");
     }
 }

Error = No overload for method Box' takes 1' arguments

Used google, no fix. I've used GUI.Box plenty of times before, I don't know why it's derping on this project.