[jquery] drag'n'drop con zindex

[mlipreri]

Ciao, sto provando il drag'n'drop in jquery, quando trascino un elemento contenuto in sliderGallery in droparea l'immagine draggata scompare appena esco dal div sliderGallery. Vorrei che restasse sempre in primo piano nella pagina, sopra a tutti gli altri div.
Ho provato a settare zindex ma niente.
Qualche aiuto?

javscript

$(document).ready(function(){	
	$(".items").draggable({helper: 'clone', zIndex: 200 });
}

html

        <div class="sliderGallery">
            <ul>[*]<span class="items" id="1">[img]images/pb_airport_express.jpg[/img]</span>[*]<span class="items" id="2">[img]images/pb_airport_extreme.jpg[/img]</span>[*]<span class="items" id="3">[img]images/pb_timecapsule_20080115.jpg[/img]</span>[*]<span class="items" id="4">[img]images/pb_keyboards20070807.jpg[/img]</span>[*]<span class="items" id="5">[img]images/pb_mighty_mouse.jpg[/img]</span>                [/list]
            
        </div>
<div class="droparea" id="droparea"></div>

css

.sliderGallery {
    overflow: hidden;
    position: relative;
    padding: 10px;
    height: 160px;
    border: 2px solid #CCCCCC;
    margin-bottom:10px;
}

.sliderGallery UL {
    position: absolute;
    list-style: none;
    overflow: none;
    white-space: nowrap;
    padding: 0;
    margin: 0;
}

.sliderGallery UL LI {
    display: inline;
}

/* DROPAREA */
.droparea {
	margin-top:10px;
	margin-bottom:10px;
	background-color: #CCCCCC;
	border: 1px solid #AAAAAA;
	min-height: 200px;
}     

.items {
}