jQuery effects' addClass() not chainable?

Hi!
I just tried something like this:
$('.flash:not(.fade)')
.addClass('fade', 1000)
.fadeOut(2000);
Firebug spits out:
$(".flash:not(.fade)").addClass("fade", 1000) has no properties
[Break on this error] .addClass('fade', 1000)
It seems like jQuery effects' addClass()-method does not return a
jquery-object. Is this intended or shall I file a bug?
Cheers, Christoph