Main menu not showing up

I have writen a script to make a main menu for my little game, but the accual menu part of the script does not show the GUI when it is exicuted. I have run through it a few times now and I cannot find what is causing the problem. Anyone have any ideas as to what is going on?

 using UnityEngine;
 using System.Collections;
 
 public class MenuSystem : MonoBehaviour {
 
     public string[] options = new string[] {"Resume"};
     private bool showMenu = false;
 
     void OnGUI()
     {
         if (GUI.Button (new Rect(2,2,Screen.width * 0.08f,Screen.height * 0.05f),"Pause"))
         {
             showMenu = true;
         }
 
         if (showMenu == true)
         {
             MainMenu(options);
             Time.timeScale = 0;
 
         }
     }
     
     void MainMenu(string[] menuButtons)
     {
         GUI.Box(new Rect(Screen.width * 0.4f, Screen.height * 0.3f,Screen.width * 0.2f, Screen.height * 0.4f), "Menu");
 
         int menuGrid = 0;
         menuGrid = GUI.SelectionGrid(new Rect(Screen.width * 0.42f, Screen.height * 0.35f, Screen.width * 0.16f, Screen.height * 0.3f), menuGrid, menuButtons, 1);
 
         switch (menuGrid)
         {
         case 0:
             showMenu = false;
             break;
         case 1:
             break;
         default:
             print("Something went wrong...");
             break;
         }
     }
 }