Delphi-PRAXiS - Delphi Uhr nach zeiteingabe läuft nicht

Hallo!

Leider läuft meine uhr nicht nach eingabe meiner zeit...
dacht das macht der ttimer...
Delphi-Quellcode:
			var mx,my:integer;

    hour, min, sec, msec  : byte;

    zeile: string;

    MyTime: TDatetime;

//Uhrzeit stellen-----------------------------------------------

Procedure TForm2.Zeit;

begin

  zeile := EdUhr.Text;

  try

    hour := StrtoInt(copy(zeile,1,2));

    Min := StrtoInt(copy(zeile,4,2));

    Sec := StrtoInt(copy(zeile,7,2));

  except

    ShowMessage('Falsche Eingabe');

    exit;

  end;

  if hour >= 24 then hour := 0;

  if Min >= 60 then Min := 0;

  if Sec >= 60 then Sec := 0;

  MyTime := EncodeTime(hour,min,sec,msec);

end;

procedure TForm2.Button1Click(Sender: TObject);

begin

Zeit;

end;

//digtaluhr und mitte bestimmen--------------------------------

procedure TForm2.Timer1Timer(Sender: TObject);

var winkel : real;

    x, y, r, i: Integer;

    hour, min, sec, msec : Word;

begin

 Form2.Caption:=TimeToStr(mytime);

 decodetime(mytime,hour,min,sec,msec);

 r:=((mx+my)div 4);

 mx := Width  div 2;

 my := Height div 2;

 refresh;

//Stundenstriche ------------------------------------------

with canvas do begin

  pen.Width:=3;

  pen.Color:=clblack;

  moveto(mx,my-width div 4);

  lineto(mx,my-width div 5);

  pen.Width:=3;

  pen.Color:=clblack;

  moveto(mx-width div 4,my);

  lineto(mx-width div 5,my);

  pen.Width:=3;

  pen.Color:=clblack;

  moveto(mx+width div 4,my);

  lineto(mx+width div 5,my);

  pen.Width:=3;

  pen.Color:=clblack;

  moveto(mx,my+width div 4);

  lineto(mx,my+width div 5);

// Sekundenzeiger------------------------------------------

 winkel:=sec* ((2*pi) / 60) - pi/2;

 x:=Trunc(cos(winkel)*r);

 y:=Trunc(sin(winkel)*r);

 x:=x+(mx);

 y:=y+(my);

 Canvas.Pen.Color:=clblack;

 Canvas.Pen.Width:=1;

 Canvas.MoveTo(mx,my);

 Canvas.LineTo(x,y);

//Minutenzeiger------------------------------------------

 winkel:=min* ((2*pi) / 60) - pi/2;

 x:=Trunc(cos(winkel)*r*0.9);

 y:=Trunc(sin(winkel)*r*0.9);

 x:=x+(mx);

 y:=y+(my);

 Canvas.Pen.Width:=2;

 Canvas.MoveTo(mx,my);

 Canvas.LineTo(x,y);

//Stundenzeiger------------------------------------------

 IF hour>12 THEN hour:=hour-12;

 winkel:=(hour*(2*pi) / 12) + (min*(2*pi) / 720) - pi/2;

 x:=Trunc(cos(winkel)*r*0.8);

 y:=Trunc(sin(winkel)*r*0.8);

 x:=x+(mx);

 y:=y+(my);

 Canvas.Pen.Width:=3;

 Canvas.MoveTo(mx,my);

 Canvas.LineTo(x,y);

end;

end;

end.