FullCalendar not showing extraParams

I am having some problems retrieving these from my string

here is my script, taken from the website.

  events: {
            url: '/CalendarManager/Findall',
            method: 'GET',
            extraParams: {
                custom_param1: 'customerName',
                custom_param2: 'description'
            },
            failure: function () {
                alert('there was an error while fetching events!');
            },
            eventRender: function (event, element) {
                element.qtip({
                    content: event.custom_param1,
                    content: event.custom_param2
                });
            }
        },