update data in chart (dropdown)

In my code below, the data is updated but the chart is not redrawn in the same position. What is the problem in my code?

(more information in firebug if you want - json is updated when the las dropdown is changed - only the category designer have data)

 <script type="text/javascript">
    dojo.query(".estatistica").onchange(function() {
        dojo.xhrPost({
            url: "drop2.php",
            handleAs: "json",
            postData: "data=" + $(this).val(),
            preventCache: true,
            load: function(json) {
                $msgs = [];

                for (var i = 1; i < 10; i++) {
                    $msgs.push(parseFloat(json[i]["valor" + i]));
                }
                var chart1 = new dojox.charting.Chart2D('chart1');
                chart1.addPlot("default", {
                    type: "StackedAreas",
                    markers: true,
                    tension: "S",
                    lines: true,
                    areas: true,
                    labelOffset: 0,

                });
                chart1.addAxis('x');
                chart1.addAxis('y', {
                    vertical: true,
                    max: 80000
                });

                chart1.addSeries('January Visits', $msgs, {
                    stroke: 'red',
                    fill: 'pink'
                });


                chart1.updateSeries("January Visits", $msgs);
 开发者_Python百科               chart1.render();


            var stackedAreaLegend = new dojox.charting.widget.SelectableLegend({
                chart: chart1
            }, "legend1");

            stackedAreaLegend.refresh();

            }
        });
    });
</script>

thanks

First, render your chart, then do any updates. Just switch these two lines, as shown:

            chart1.render();
            chart1.updateSeries("January Visits", $msgs);