function GetFileLastModifiedTimeStap(const FileName: string) : TDateTime;
var
  FileHandle : THandle;
  DateInfo: TFileTime;
  SysTimeStruct: SYSTEMTIME;
  TimeZoneInfo: TTimeZoneInformation;
  Bias: Double;
begin
  Result := 2; //01.01.1900 00:00:00
  Bias := 0;
  FileHandle := FileOpen(FileName, fmOpenRead or fmShareDenyWrite);
  if FileHandle > 0 then
  begin
    try
      if GetTimeZoneInformation(TimeZoneInfo) <> $FFFFFFFF then Bias := TimeZoneInfo.Bias / 1440; // 60x24
      GetFileTime(FileHandle, nil, nil, @DateInfo);
      if FileTimeToSystemTime(DateInfo, SysTimeStruct) then result := SystemTimeToDateTime(SysTimeStruct) - Bias;
    finally
      FileClose(FileHandle);
    end;
  end;
end;