trying to get a simple jquery slideshow to work in jsfiddle

trying to get a simple jquery slideshow to work in jsfiddle

using the code from http://jonraasch.com/blog/a-simple-jquery-slideshow
I have created a jsfiddle.
problem is the slideshow is not working in the jsfiddle so I cant then
adapt it for my needs
anyone see what the problem is
http://jsfiddle.net/UUKP4/8/
code
function slideSwitch() {
var $active = $('#slideshow IMG.active');
if ( $active.length == 0 ) $active = $('#slideshow IMG:last');
// use this to pull the images in the order they appear in the
markup
var $next = $active.next().length ? $active.next()
: $('#slideshow IMG:first');
$active.addClass('last-active');
$next.css({opacity: 0.0})
.addClass('active')
.animate({opacity: 1.0}, 1000, function() {
$active.removeClass('active last-active');
});
}
$(function() {
setInterval( "slideSwitch()", 5000 );
});
</script>
<style type="text/css">
/*** set the width and height to match your images **/
#slideshow {
position:relative;
height:350px;
}
#slideshow IMG {
position:absolute;
top:0;
left:0;
z-index:8;
opacity:0.0;
}
#slideshow IMG.active {
z-index:10;
opacity:1.0;
}
#slideshow IMG.last-active {
z-index:9;
}
</style>
<div id="slideshow">
<img src="image1.jpg" alt="Slideshow Image 1" class="active" />
<img src="image2.jpg" alt="Slideshow Image 2" />
<img src="image3.jpg" alt="Slideshow Image 3" />
<img src="image4.jpg" alt="Slideshow Image 4" />
</div>