Background Events via JSON - fullcalendar

Question

How do I indicate an event as being a background event within a JSON feed (which I'm creating through AJAX). It is being rendered as a regular event, not a Background event.
JSON Feed:
[{"id":"availableForMeeting","start":"2015-02-04T09:00:00","end":"2015-02-04T20:00:00","rendering":"background","overlap":true},{"title":"Working","start":"2015-02-04T10:00:00","end":"2015-02-04T12:00:00","allDay":false,"overlap":true},{"title":"Lunch","start":"2015-02-04T12:00:00","end":"2015-02-04T14:00:00","allDay":false},{"title":"Working","start":"2015-02-04T14:00:00","end":"2015-02-04T19:00:00","allDay":false}]

Answer 1

You can do this in FullCalendar 2.2+ using Background Events by adding rendering: 'background' to the event (documentation). In the example below, it'd be the same for the JSON feed.
Since you stated you are indeed using rendering: 'background', I would check that
1) You are using the correct version of FullCalendar
2) There are no errors on the page
3) If neither 1 or 2, post a code snippet that shows your problem, since the one below works fine:
Also note that per the docs:
Background events that are timed will only be rendered on the time
slots in agenda view. Background events that are all-day will only be
rendered in month view or the all-day slots of agenda view.
$('#fullCal').fullCalendar({
events: [{
title: 'Main Event',
start: moment().add(3, 'h'),
end: moment().add(5, 'h'),
color:'#ff0000',
allDay: false
}, {
start: moment().add(1, 'h'),
end: moment().add(10, 'h'),
rendering: 'background'
}, {
title: 'Other Event',
start: moment().add(6, 'h'),
end: moment().add(8, 'h'),
color:'#00cc00',
allDay: false
}],
header: {
left: '',
center: 'prev title next',
right: ''
},
timezone:'local',
defaultView: 'agendaWeek'
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.0/jquery.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.8.3/moment.min.js"></script>
<link href="https://cdnjs.cloudflare.com/ajax/libs/fullcalendar/2.2.0/fullcalendar.min.css" rel="stylesheet" />
<script src="https://cdnjs.cloudflare.com/ajax/libs/fullcalendar/2.2.0/fullcalendar.min.js"></script>
<div id="fullCal"></div>