created a button that clicks the window (Delete) panel. Bottom script.

using system.collections;
Using System.Collections.Genic;
using unityengine;
Public Class Actions: Monobehaviour
{
  Public Void Delete ()
  {
    // int ID = GameObject.Transform.Parent.getcomponent & lt; ID & GT; (). ID;
    GameObject Deletewindow = GameObject.find ("Window (Delete)");
    Print (Deletewindow);
    //Deletewindow.getcomponent<delete> ;().id = id;
    //Deletewindow.setActive(True);
  }
}

To my surprise, the result is returned empty and because of this pops error

NULLReferenceException: Object Reference Not Set to An Instance of An Object

Screenshot here and below.

Such errors began to meet with me often.
Finally someone tell me – where is my mistake?

Answer 1, Authority 100%

GameObject.find Lookages only active objects. And you have this panel, judging by the screen, turned off.

Try search with Resources.findObjectSoftypeall . It seems like inactive objects will also return.