我想晚一点到$latetime1返回正确，但$latetime2返回的值与$latetime1不同$systemintime值格式和$intime值格式相同。但我得到以上的错误$latetime2。什么应该是正确的，请有人帮帮我。下面是我的函数-

public function update(Request $request, Attendance $attendance)
{
    $attendance = Attendance::find($attendance->id);
    $inTime = $attendance->intime;
    // late time caculate
    $systemIntime = DB::table('schools')
                     ->join('users', 'schools.id', '=', 'users.school_id')
                     ->select('schools.intime')
                     ->first();
    $latetime1 = (new \DateTime($inTime))->format('H:i:s');
    $latetime2 = (new \DateTime($systemIntime))->format('H:i:s');
    $late      = $latetime1->diff($latetime2);