var series = new System.Windows.Forms.DataVisualization.Charting.Series();
            series.ChartType = SeriesChartType.Line;
            series.Points.DataBind(dv1, "DateCreated", "Visibility", "");
            chart1.Series[0].MarkerStyle = MarkerStyle.Diamond;
            chart1.Series[0].MarkerSize = 100;
            chart1.Series[0].IsValueShownAsLabel = true;
            chart1.Series[0].MarkerColor = Color.Red;
            chart1.Series.Add(series);
            chart1.SaveImage(pdfFile, ChartImageFormat.Png);