How to get the window title receiver with WinApi

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Runtime.InteropServices;


namespace parol_udal
{
    class Program
    {
        [DllImport("user32.dll",CharSet=CharSet.Auto,SetLastError=true)]
        public static extern IntPtr FindWindow(string sClassName,string sWindowName);

        [DllImport("user32.dll",CharSet=CharSet.Auto,SetLastError=true)]
         public static extern IntPtr FindWindowEx(IntPtr hwndParent, IntPtr hwndChildAfter, string lpClassName, string lpWindowName);

        [DllImport("user32.dll",CharSet=CharSet.Auto ,SetLastError = true)]
        public static extern int GetWindowText (IntPtr hwnd,StringBuilder lpString,int nMaxCount);

        [DllImport("user32.dll",CharSet=CharSet.Auto, SetLastError = true)]
        static extern int GetWindowTextLength(IntPtr hWnd);
        
        static void Main()
        {
           IntPtr thisWindow = FindWindow(null, "Window description Parent");
           IntPtr Rod = thisWindow;
                      
           IntPtr otherWindow = FindWindowEx(Rod, IntPtr.Zero, "RICHEDIT50W", null);
        
                        
            int len = GetWindowTextLength(otherWindow);
            StringBuilder sb = new StringBuilder(len);
            len = GetWindowText(otherWindow, sb, len);

            Console.WriteLine(sb.ToString(0,len)); //get empty string
            Console.WriteLine(thisWindow); //get parent description
            Console.WriteLine(otherWindow);//get receivery description
            Console.ReadKey(true); 
       }
    }
}
Please help, how to get title "otherWindow"?