MSChart becomes blank after update

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C#

ASP.NET

Ajax

chart

Hi, I have a user control which contains an MSChart. I have a drop down list using which I want to select series that I have defined in the code behind. I have used Update Panels, both in the Chart Area as well as on the main .aspx page. After raising the "OnSelectedIndexChanged" event I used a Delegate to Update the UpdatePanel in the .aspx page as well as using Update() in the .ascx page. The chart does not refresh with the new series and just remains blank.

Here is the relevant code

.ascx file

protected void ChangeSeries(object sender, EventArgs e)
        {
            string series_selected = dd1.SelectedIndex.ToString();

                       
            switch (series_selected)
            {
                case ("Points"):
                    Series series1 = Chart1.Series[0];
                    this.FillStockDataPoints(series1, 5.0, DateTime.Now);
                    this.Chart1.Series["series1"].ChartType = System.Web.UI.DataVisualization.Charting.SeriesChartType.Line;
                    Chart1.Series[0]["PixelPointWidth"] = "25";
                    _delUpdateControl.DynamicInvoke();
                   UpdatePanel1.Update() 
                    
                    break;

                case ("CSAT"):
                    Series series2 = Chart1.Series[1];
                    this.FillStockDataCSAT(series2, 5.0, DateTime.Now);
                    Chart1.Series[1]["PixelPointWidth"] = "25";
                    this.Chart1.Series["series2"].ChartType = System.Web.UI.DataVisualization.Charting.SeriesChartType.Column;
                    _delUpdateControl.DynamicInvoke();
                    UpdatePanel1.Update()
                    break;

                case ("SLA"):
                    Series series3 = Chart1.Series[2];
                    this.FillStockDataSLA(series3, 5.0, DateTime.Now);
                    Chart1.Series[2]["PixelPointWidth"] = "25";
                    this.Chart1.Series["series3"].ChartType = System.Web.UI.DataVisualization.Charting.SeriesChartType.Column;
                    _delUpdateControl.DynamicInvoke();
                    UpdatePanel1.Update()
                    break;
            }

This is the Dynamic Invoke Delegate:

public void UpdateStatsControl()
        {
            this.UpdatePanelStats.Update();
            StatsControl.InitializeStatsControl();

        }

Please tell me a way to refresh and reload the Chart after selecting the required series in the DropDownList.

HELP!!!!