我想為登入的用戶添加事件到行事曆內，看了這部分的用法還是不太明白
https://developers.google.com/calendar/create-events

// Refer to the PHP quickstart on how to setup the environment:
// https://developers.google.com/calendar/quickstart/php
// Change the scope to Google_Service_Calendar::CALENDAR and delete any stored
// credentials.

$event = new Google_Service_Calendar_Event(array(
  'summary' => 'Google I/O 2015',
  'location' => '800 Howard St., San Francisco, CA 94103',
  'description' => 'A chance to hear more about Google\'s developer products.',
  'start' => array(
    'dateTime' => '2015-05-28T09:00:00-07:00',
    'timeZone' => 'America/Los_Angeles',
  ),
  'end' => array(
    'dateTime' => '2015-05-28T17:00:00-07:00',
    'timeZone' => 'America/Los_Angeles',
  ),
  'recurrence' => array(
    'RRULE:FREQ=DAILY;COUNT=2'
  ),
  'attendees' => array(
    array('email' => 'lpage@example.com'),
    array('email' => 'sbrin@example.com'),
  ),
  'reminders' => array(
    'useDefault' => FALSE,
    'overrides' => array(
      array('method' => 'email', 'minutes' => 24 * 60),
      array('method' => 'popup', 'minutes' => 10),
    ),
  ),
));

$calendarId = 'primary';
$event = $service->events->insert($calendarId, $event);
printf('Event created: %s\n', $event->htmlLink);

執行後出現了這樣的錯誤
Fatal error: Uncaught Error: Call to a member function insert() on null in D:\website\htdocs\google\login\client.php:33 Stack trace: #0 {main} thrown in D:\website\htdocs\google\login\client.php on line 33
有沒有用過這部分的大大可以幫幫我