[jQuery] Add an animate function to a addClass?

[jQuery] Add an animate function to a addClass?


Hi all,
why doesn't this work? it doesn't color red
$.fn.hoverClass = function(c) {
            return this.each(function(){
                $(this).hover(
                    function() { $(this).addClass(c).animate({ marginLeft: '+=5px' },
200); },
                    function() { $(this).removeClass(c).animate({ marginLeft: '-
=5px' }, 200); }
                );
            });
        };
.navHover {
background-color:#FF0000;
}