Php jQuery FullCalendar不'；在FireFox 33.0中不显示事件问题

我正试图通过FullCalendarevents函数以json提要的形式提供数据，从而设置jQuery FullCalendar。基本上这是我的js代码：

var calendar = $('#calendar').fullCalendar({

  editable: true,
  firstDay: 1,
  header: {
    left: 'prev, next today',
    center: 'title',
    right: 'month, agendaWeek, agendaDay'
  },

  events: 
  {
    url: 'events.php',
    type: 'POST',
    cache: false,
    error: function() {
      alert('ERROR');
    },
    color: 'blue'
  }
});

我的代码来自events.php，它从数据库中提取数据，并将日期转换为文档中的sayd格式的ISO8601日期字符串

// Query that retrieves events
$q = "SELECT * FROM evenement ORDER by id";
$r = mysqli_query($dbc, $q);
while ($row = mysqli_fetch_assoc($r)) 
{
    $s = new DateTime($row['start']);
    $e = new DateTime($row['end']);
    $row['start'] = $s->format(DATE_ISO8601);
    $row['end']   = $e->format(DATE_ISO8601);
    $json[] = $row;
}

echo json_encode($json);

在IE11和Chrome中，它显示日历中的所有事件，而在FireFox中，日历是空的。。返回的响应JSON字符串为：

[
{"id":"7","title":"Rino","start":"2014-10-22T11:55:46+0300","end":"2014-10-22T11:55:46+0300","url":"nav","allDay":"false"},
{"id":"8","title":"Rin","start":"2014-10-22T13:01:45+0300","end":"2014-10-22T13:01:45+0300","url":"Hello","allDay":"false"},
{"id":"9","title":"Rino","start":"2014-10-23T10:06:22+0300","end":"2014-10-23T10:06:22+0300","url":"Hello","allDay":"false"},
{"id":"10","title":"a","start":"2014-10-23T09:42:04+0300","end":"2014-10-23T09:42:04+0300","url":"a","allDay":"false"},
{"id":"11","title":"1","start":"2014-10-23T09:41:55+0300","end":"2014-10-23T09:41:55+0300","url":"1","allDay":"false"},
{"id":"12","title":"sdas","start":"2014-10-23T10:06:14+0300","end":"2014-10-23T10:06:14+0300","url":"1","allDay":"false"},
{"id":"13","title":"Prju","start":"2014-10-16T00:00:00+0300","end":"2014-10-17T00:00:00+0300","url":"undefined","allDay":"false"}
]

---

我遗漏了什么，为什么在Firefox中它没有显示任何事件？我也尝试过清除缓存等。。但是没有任何结果

即使你在本地设置数据，你也能提供一把小提琴吗？我刚刚注意到一件有趣的事情。当我打开firebug并在当前页面中执行某些操作后，事件将从页面中消失。后来内容就消失了。重新打开浏览器后，内容将返回。通过禁用firebug，一切又恢复正常了……我没有注意到任何奇怪的事情，即使firebug打开了，我也试过小提琴，效果很好。而且，即使在FireFox中，如果我在事件中手动编写JSON字符串，比如在fiddle中完成，它也可以正常工作。但如果我从不同的页面获取JSON字符串，就像我试图做的那样，那么就会出现firebug故障。