Creating Charts with multiple series in Powerpoint 2013 using C#

Question

I am using VS2013 Ultimate, with Office 2013 (PowerPoint, Excel and Word all installed). I am coding in C#.

I am creating a PowerPoint presentation using C#. So far, I have managed to accomplish everything that I have wanted to do. However, I am having problems attempting to create a chart. My understanding is that Excel is used to manage the data (in a worksheet). I have the following code, which will produce a chart with two series in a PowerPoint slide. The problem is that 'sometimes' the chart does not get added to the slide. It gets added, the worksheet appears and the data is modified and the chart disappears from the slide! I also notice 2 instances of Excel firing up but I cannot understand why. Can anyone shed any light on this please? Thanks.

public void CreateChart(PPT.Slide slide)
    {
        slide.Layout = PPT.PpSlideLayout.ppLayoutBlank;

        var chart = slide.Shapes.AddChart(XlChartType.xlLine, 10f, 10f, 900f, 400f).Chart;

        var workbook = (EXCEL.Workbook)chart.ChartData.Workbook;
        workbook.Windows.Application.Visible = true;

        var dataSheet = (EXCEL.Worksheet)workbook.Worksheets[1];
        dataSheet.Cells.ClearContents();


        dataSheet.Cells.Range["A1"].Value2 = "Bananas";
        dataSheet.Cells.Range["A2"].Value2 = "Apples";
        dataSheet.Cells.Range["A3"].Value2 = "Pears";
        dataSheet.Cells.Range["A4"].Value2 = "Oranges";
        dataSheet.Cells.Range["B1"].Value2 = "1000";
        dataSheet.Cells.Range["B2"].Value2 = "2500";
        dataSheet.Cells.Range["B3"].Value2 = "4000";
        dataSheet.Cells.Range["B4"].Value2 = "3000";

        var sc = (PPT.SeriesCollection)chart.SeriesCollection();

        do
        {
            var seriesToDelete = sc.Item(1);
            seriesToDelete.Delete();
        }
        while (sc.Count != 0);

        var series1 = sc.NewSeries();
        series1.Name = "Pauls Series";
        series1.XValues = "'Sheet1'!$A$1:$A$2";
        series1.Values = "'Sheet1'!$B$1:$B$2";
        series1.ChartType = XlChartType.xlLine;

        var series2 = sc.NewSeries();
        series2.Name = "Seans Series";
        series2.XValues = "'Sheet1'!$A$1:$A$2";
        series2.Values = "'Sheet1'!$B$3:$B$4";
        series2.ChartType = XlChartType.xlLine; 

        chart.HasTitle = true;
        chart.ChartTitle.Font.Italic = true;
        chart.ChartTitle.Text = "My First Chart!";
        chart.ChartTitle.Font.Size = 12;
        chart.ChartTitle.Font.Color = Color.Black.ToArgb();
        chart.ChartTitle.Format.Line.Visible = Microsoft.Office.Core.MsoTriState.msoTrue;
        chart.ChartTitle.Format.Line.ForeColor.RGB = Color.Black.ToArgb();

        chart.HasLegend = true;
        chart.Legend.Font.Italic = true;
        chart.Legend.Font.Size = 10;

        chart.Refresh();


    }

Answer 1

so, putting a chart.refresh() within the Do{} block has resolved my problems! How odd!?!