Adding a class to an object is not applying the CSS for some reason

Adding a class to an object is not applying the CSS for some reason

In the code below I am trying to add a class to an object. When I click on the element, the alert shows the name of the class, but the color from the CSS is not changing. What am I doing wrong this time???

  1.       // Get ID of the agenda item from the event object
            var agendaId = eventObj.data.agendaId;       
            // pull agenda item from calendar
            var agendaItem = jfcalplugin.getAgendaItemById("#mycal",agendaId);
            clickAgendaItem = agendaItem;
            $(clickAgendaItem).attr("class","fullFlagLate");
            alert("In the myAgendaClickHandler " + $(clickAgendaItem).attr("class"));
            $.each(clickAgendaItem, function(key, element) {
                alert('key: ' + key + ' value: ' + element);
            });