for some reason, after a couple of seconds the clicked on div acquires the "fade" class even though in theory it is still a "div-selected" and not a div:not(.div-selected)...what am I missing???

1. $(".content-item").click(
2. function(){
3.  $(this).addClass('div-selected', 500);
4.   $('div:not(.div-selected)').addClass('fade').show('slow');
5.   $(this).css("z-index","100")
6. }
7.  
8.  );