更新与会者响应状态-谷歌日历API(PHP）

我制作了一个使用Google Calendar API和Oauth2的小应用程序。现在，我想允许用户在活动中回答。这是我的代码：

PHP

if(isset($_POST['submit'])){
    $eventSubmit = $service->events->get('primary', $_POST['eventID']);
    $attendeesSubmit=$eventSubmit->getAttendees();
    foreach ($attendees as $attendee) {
        $mailSubmit = $attendee->getEmail();
        if ($mailSubmit==$emailUser){
            if ($_POST['status']=='accepte'){
               $attendee->setResponseStatus('accepted');
               $service->events->update('primary', $_POST['eventID'], $eventSubmit);
            }
            if ($_POST['status']=='decline'){
                $attendee->setResponseStatus('decline');
            }
        }
}

HTML

    <form method="post" action="index.php">
    <input type="radio" name="status" id="accepte" value="accepte">Confirmer</input>
    <input type="radio" name="status" id="decline" value="decline">Décliner</input>
    <input type="hidden" name="eventID" value="<?php echo htmlspecialchars($event['id']); ?>">
    <input type="submit" name="submit" value="OK"></br></br>

但它不起作用，当我提交表单时，用户的回复状态不会改变。这是怎么回事？