Editor Script Disable Toggle C#

Good Afternoon, I am trying to disable a editor toggle button in the inspector by code and make it not clickable. Thanks for all your help.

using UnityEngine;
using UnityEditor;
using System.Collections;

[CustomEditor (typeof (Tester))]
public class Test : Editor {

private bool test;

public override void OnInspectorGUI() {

test = EditorGUILayout.Toggle("test", test);

}

}

using UnityEditor;

[CustomEditor (typeof (Tester))]
public class Test : Editor {
	
	bool test;
	bool disabled;
	Tester tester;
	void OnEnable(){
		tester = (Tester)target;
	}
	public override void OnInspectorGUI() {

		test = EditorGUILayout.Toggle("test", test);
		EditorGUI.BeginDisabledGroup (test == false);
		disabled = EditorGUILayout.Toggle("disabled", disabled);
		EditorGUI.EndDisabledGroup ();
	}
}