The problem:
"...The problem is that the calendar is initialized while the modal or div is not visible... " based on this link enter link description here
In my opinion, destroy is not needed in this case, only with render you can see the calendar.
My solution:
<script type="text/javascript">
$('#objectname').show(0,onObjectShow);
function onObjectShow(){$('#calendar').fullCalendar('render');}
</script>
You must to be sure that the object(container of calendar) is fully visible. For example, my first mistake was to put this code on "onClick" event, and click event is triggered before show the object container and has no effect.
Solution Based on this reference.