帮忙检查一下代码错误

我想在form1窗体中label1.caption上,显示剩余时间,你们帮忙看看那错了?
procedure Tform1.FormDeactivate(Sender: TObject);
var
  Reg:Tregistry;
  KeyName,TempCode,TempName,TempStr:string;
  Same:Integer;
  FirstDate,NowDate,RegNowDate:Tdate;
  NumberOfDays:real;
begin
  NoRegistry:=true;
  NowDate:=date; //取得运行时系统日期
  try
  //创建注册表，有该键则读取，无则创建
     Reg:=Tregistry.Create;
     Reg.RootKey :=hkey_local_machine;
     KeyName:='Software';     if Reg.OpenKey(KeyName,true) then
     begin
        try
          FirstDate:=Reg.ReadDate('Date');
          //非第一次则读入第一次运行时间
        except
          Reg.WriteDate('Date',NowDate);
          // 若为第一次运行，则写入系统日期
          FirstDate:=NowDate;
        end;
        try
          RegNowDate:=Reg.ReadDate('RegNowDate');
          if Nowdate < RegNowDate then
          begin
            showmessage('您更改了系统时间，程序未注册并超过试用期将终止运行!');
            application.Terminate;//禁止运行
          end
          else
          begin
            Reg.WriteDate('RegNowDate',NowDate);
          end;
        except
          Reg.WriteDate('RegNowDate',NowDate);
        end;
     end;
     reg.CloseKey;
  finally
     reg.Free;
  end;
  NumberOfDays:=Nowdate-FirstDate;
  label1.caption:='你现在使用时间是:'+floatTOstr(NumberOfDays);
end;