Ereignis bei message abfangen geht nicht

[KuH_am_SchuH]

warum geht das hier denn nicht ??? :

Delphi-Quellcode:

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls,shellapi,ExtCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Timer1: TTimer;
    procedure Button1Click(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { Private-Deklarationen }
  public
    { Public-Deklarationen }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
var
msg : TMSG;


procedure TForm1.Button1Click(Sender: TObject);
begin
sendmessage(application.Handle,WM_SyScommand,sc_Screensave,0)
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
 if msg.message = WM_SYSCOMMAND then begin
 shellexecute(handle,nil,'notepad',nil,nil,SW_SHOWNORMAL)
 enD;
 end;

end.

helft mir bitte^^