Slider not moving on drag

Slider not moving on drag


I'm just trying to get the hang of the ui slider. Seems like it should
be easy enough, but I'm running into a problem. When I drag on the
handle, I get the following error in Firefox 3.0.1:
Warning: Error in parsing value for property 'left'. Declaration
dropped.
My setup is pretty simple, and I I'm using the latest versions of
jQuery, ui.core and ui.slider (the ui functions were downloaded as
separate personalized packages.)
HTML:
<!-- Years Experience -->
        <div id="slider_bar" class="slider_bar">
            <div class="slider_handle"></div>
        </div>
CSS:
/* slider */
.slider_bar {
    background: transparent url(/public/images/widgets/slider/slider-
bar.gif) top left no-repeat;
    height: 19px;
    width: 260px;
    position: relative;
    margin: 0 5px;
    z-index: 50;
}
.slider_handle {
    background: transparent url(/public/images/widgets/slider/slider-
handle.png) top left no-repeat;
    height: 19px;
    width: 20px;
    overflow: hidden;
    position: absolute;
    top: 1px;
    left: 0;
    z-index: 55;
}
SCRIPT:
<script type="text/javascript" language="Javascript">
    $(document).ready(function() {
        $("#slider_bar").slider({
            handle:    'slider_handle',
            minValue: 0,
            maxValue: 30,
            start:     function (e, ui) {
                console.log("started!");
            }
        });
    });
</script>
Any ideas? Thanks!