Unable To Find Style in Gameskin/Layout

Hey. I am new to Unity and I’m trying to make a small game. This is a script for my pause button, and I am trying to make a Pause Menu using GUI.Window. The game pauses but the menu doesn’t appear. There is a warning in the window saying Unable to find style ‘Gstyle’ in skin ‘GameSkin’ Repaint and also Unable to find style ‘Gstyle’ in skin ‘GameSkin’ layout. I don’t really know what to do so please help me out?

using UnityEngine;
    using System.Collections;
    
    public class PauseScript : MonoBehaviour {
    	private bool paused;
    	public GUIText lala;
    	public GUIStyle Gstyle;
    	int buttonwidth =150;
    	int bheight=150;
    	int abc;
    	Rect pmen = new Rect(10,10,200,200);
    
    	void Start () {
    		paused = false;
    	}
    
    	void OnGUI () {
    
    		GUI.skin.GetStyle ("Gstyle");
    		GUI.skin.button = Gstyle;
    		if (GUI.Button (new Rect (Screen.width / 2 + 400, Screen.height / Screen.height-1, buttonwidth, bheight), "")) 
    		{
    			if (paused==false)
    			{
    				paused=true;
    				GUI.Window(9,pmen,MenuPause,"Pause Menu");
    				Time.timeScale=0;
    
    			
    			}
    			else{
    				paused=false;
    				Time.timeScale=1;
    
    			}
    		}
    	}
    	void MenuPause(int nid)
    	{
    		if(GUILayout.Button("Main Menu")){
    			Application.LoadLevel("MainMenu");
    		}
    		if(GUILayout.Button("Restart")){
    			Application.LoadLevel("InGame");
    		}
    		if(GUILayout.Button("Quit")){
    			Application.Quit();
    		}
    		}
    }

If you use custom GUISkin, that write:

 public GUISkin mySkin = null; //attach in this variable your skin
 ...
 void OnGUI() {
  GUI.skin = mySkin;
  //In your skin you create, for example, style for button by name "btnStyle"
  if (GUI.Button(new Rect(0, 0, 100, 100), "this a button", "btnStyle") {
   // Do something
  }
  ...
 }

If you use only GUIStyle, then write:

 public GUIStyle myStyle = null; //attach in this variable your style
 ...
 void OnGUI() {
  //You create your style, for example, for button
  if (GUI.Button(new Rect(0, 0, 100, 100), "this a button", myStyle) {
   // Do something
  }
  ...
 }

I hope it will help you.