[jQuery] on the fly div and ui droppable problem

[[EMAIL PROTECTED]]

hi all

i found a problem with jquery ui droppable,

i give the target div a css class which drag and drop is working
fine , but when i create another div with the class on the fly and
append it to the HTML the drop doesn't work

are there any solution ?
the code is like that
<script>
$(".pheader").droppable({
    accept: ".ads",
        drop: function(ev, ui) {
        ui.draggable.clone().fadeOut("fast",
        function() {
            $(this).fadeIn("fast") ;
                         }).appendTo($(this).empty());
    }
});
/*  the problem div */
$('<div class="pheader" >&nbsp;</div>').appendTo("#ground");
</script>