Using WM_Close in C #

I am using the below code to close the window by searching for the window name in the taskbar. But in one case, my window will not appear on the taskbar. In this scenario, the WM_Close

window could not be closed. Another way to do it with WM_Close

???

    void DaemonTerminamtionHook_KeyPressed(object sender, KeyPressedEventArgs e)
    {
        DaemonResult = MessageBox.Show("Are you sure, you want to Terminate Daemon?", "Terminate Daemon", MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation);

        if (DaemonResult == DialogResult.Yes)
        {
            //Free the resources of ShellBasics and terminate Daemon here.
            IntPtr hWnd = FindWindowByCaption(IntPtr.Zero, "DAEMON TAB BAR");
            bool ret = CloseWindow(hWnd);
        }
    }

    //WM_Close
    [DllImport("user32.dll", EntryPoint = "FindWindow", SetLastError = true)]
    static extern IntPtr FindWindowByCaption(IntPtr ZeroOnly, string lpWindowName);

    [DllImport("user32.dll", CharSet = CharSet.Auto)]
    static extern IntPtr SendMessage(IntPtr hWnd, UInt32 Msg, IntPtr wParam, IntPtr lParam);

    static uint WM_CLOSE = 0x10;

    static bool CloseWindow(IntPtr hWnd)
    {
        SendMessage(hWnd, WM_CLOSE, IntPtr.Zero, IntPtr.Zero); 
        return true;
    }

      

        
        
        
      

    

Now using the below code ... But getting error in

"IntPtr hWnd = PostMessage (IntPtr.Zero, WM_CLOSE, IntPtr.Zero, IntPtr.Zero);

where to give the window name to close this.

 void DaemonTerminamtionHook_KeyPressed(object sender, KeyPressedEventArgs e)
    {
        DaemonResult = MessageBox.Show("Are you sure, you want to Terminate Daemon?", "Terminate Daemon", MessageBoxButtons.YesNo, MessageBoxIcon.Exclamation);

        if (DaemonResult == DialogResult.Yes)
        {

            IntPtr hWnd = PostMessage(IntPtr.Zero, WM_CLOSE, IntPtr.Zero, IntPtr.Zero);
            bool ret = CloseWindow(hWnd);
        }
    }



    static uint WM_CLOSE = 0x10;
    [return: MarshalAs(UnmanagedType.Bool)]
    [DllImport("user32.dll", SetLastError = true)]
    static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);

    static bool CloseWindow(IntPtr hWnd)
    {
        bool returnValue = PostMessage(hWnd, WM_CLOSE, IntPtr.Zero, IntPtr.Zero);
        if (!returnValue)
            throw new Win32Exception(Marshal.GetLastWin32Error());
        return true;
    }