AddChart gives COM error

Hi,

    I'm using Windows 7, Office 2013, Visual Studio 2012.

    I'm trying to add a chart to a Powerpoint presentation but getting a COM error, using a C# program. It works fine if I open the presentation with the WithWindow parameter set to MsoTriState.msoTrue but fails with a COM error if the parameter is set to MsoTriState.msoFalse. 

    The COM error I get is 'Error HRESULT E_FAIL has been returned from a call to a COM component.' with an HRESULT of -2147467259, with no other information. Below is some code to reproduce the problem.

    Has anyone else seen this before or can anyone suggest a way to proceed please?

    Thanks,

    Kevin

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using IOPP = Microsoft.Office.Interop.PowerPoint;
using gr = Microsoft.Office.Interop.Graph;
using xl = Microsoft.Office.Interop.Excel;
using Core = Microsoft.Office.Core;

namespace Powerpointchart
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button3_Click(object sender, EventArgs e)
        {
            IOPP.Application powerpoint = new IOPP.Application();
            var presentations = powerpoint.Presentations;
            IOPP.Presentation pres = presentations.Open("C:\\templates\\PPTChart.pptx",
                                                        Microsoft.Office.Core.MsoTriState.msoTrue,
                                                        Microsoft.Office.Core.MsoTriState.msoTrue,
                                                        Microsoft.Office.Core.MsoTriState.msoFalse);

            try
            {
                //Instantiate slide object
                Microsoft.Office.Interop.PowerPoint.Slide objSlide = null;

                //Access the first slide of presentation
                objSlide = pres.Slides[1];

                IOPP.Chart ppChart = objSlide.Shapes.AddChart(Microsoft.Office.Core.XlChartType.xl3DColumn, 20F, 30F, 400F, 300F).Chart;
            }
            catch (Exception ex)
            {
                MessageBox.Show("Error: " + ex.Message);
            }
            finally
            {
                //Close Workbook and presentation
                pres.Application.Quit();
            }
        }
    }
}