[lazarus] TTimer on Win32

[Prof. Roberto A. Berrospe Machin]

Why Timers in Win32 dont work?
I try use, TTimer and TIdleTimer, but no work.
The app compiles fine, but timer not work.

This is part of my code. 

Procedure TESTTIMER_ONTIMER();
Begin
    MAINFORM.TIMELABEL.Caption := 'Test';
    Application.MessageBox('Test','test',1)
End;

Constructor MAINFORMCLASS.Create(AOwner: TComponent);
Begin
     Inherited Create(AOwner);
     Caption  := 'Timer Test';
     Width  := 120;
     Height  := 100;
    TESTTIMER := TIdleTimer.Create(Self);
    TESTTIMER.Interval  := 1000;
    TESTTIMER.OnTimer  := @TESTTIMER_ONTIMER;
End;

destructor MAINFORMCLASS.Destroy;
begin
     inherited Destroy;
end;