Преобразование даты в неделю

procedure TForm1.Button1Click(Sender: TObject);
var  frstDay,toDay : TDateTime;  week : Integer;
begin

frstDay := StrToDate('1/1/96');
toDay := StrToDate(Edit1.Text);
week := Trunc((toDay - frsont color=blue>1;
Label1.Caption := IntToStr(week);
end;