C# – Generating PDF from a DataGridView in Winforms

I'm attempting to create a PDF from a DataGridView populated from a database.

I have just started trying to learn how to use iTextSharp to accomplish this.

The result of my code is a PDF that will not open. I get an error saying "File cannot be opened"

Here is my code to generate the PDF

void SendToPDF(string heading, string filename)
    {
        try
        {
            Document doc = new Document(PageSize.A4.Rotate(), 30, 30, 20, 20);

            string myDocs = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);
            if (!Directory.Exists(myDocs + @"\Production Reports"))
                Directory.CreateDirectory(myDocs + @"\Production Reports");

            PdfWriter.GetInstance(doc, new FileStream(myDocs + @"\Production Reports\" + filename + ".pdf", FileMode.Append, FileAccess.Write));

            iTextSharp.text.Font titleFont = new iTextSharp.text.Font(iTextSharp.text.Font.FontFamily.HELVETICA, 14.0F, iTextSharp.text.Font.BOLD, BaseColor.BLACK);

            iTextSharp.text.Font tableFont = new iTextSharp.text.Font(iTextSharp.text.Font.FontFamily.HELVETICA, 12.0F, iTextSharp.text.Font.NORMAL, BaseColor.BLACK);

            iTextSharp.text.Font headerfont = new iTextSharp.text.Font(iTextSharp.text.Font.FontFamily.HELVETICA, 12.0F, iTextSharp.text.Font.BOLD, BaseColor.BLACK);

            PdfPTable table = new PdfPTable(GridView.Columns.Count);
            //table.TotalWidth = GridView.Width;

            //There are ALWAYS 10 columns

            float[] widths = new float[] { GridView.Columns[0].Width, GridView.Columns[1].Width, GridView.Columns[2].Width, 
                                           GridView.Columns[3].Width, GridView.Columns[4].Width, GridView.Columns[5].Width,
                                           GridView.Columns[6].Width, GridView.Columns[7].Width, GridView.Columns[8].Width,
                                           GridView.Columns[9].Width };
            table.SetWidths(widths);
            table.HorizontalAlignment = 1; // 0 - left, 1 - center, 2 - right;
            table.SpacingBefore = 2.0F;

            PdfPCell cell = null;

            doc.Open();
            Phrase p = new Phrase(new Chunk(heading, titleFont));
            doc.Add(p);

            foreach (DataGridViewColumn c in GridView.Columns)
            {
                cell = new PdfPCell(new Phrase(new Chunk(c.HeaderText, headerfont)));
                cell.HorizontalAlignment = PdfPCell.ALIGN_CENTER;
                cell.VerticalAlignment = PdfPCell.ALIGN_CENTER;
                table.AddCell(cell);
            }

            if (GridView.Rows.Count > 0)
            {
                for (int i = 0; i < GridView.Rows.Count - 1; i++)
                {
                    for (int j = 0; j < GridView.Columns.Count - 1; j++)
                    {
                        cell = new PdfPCell(new Phrase(GridView.Rows[i].Cells[j].Value.ToString(), tableFont));
                        cell.HorizontalAlignment = PdfPCell.ALIGN_CENTER;
                        cell.VerticalAlignment = PdfPCell.ALIGN_CENTER;
                        table.AddCell(cell);
                    }
                }
            }
            doc.Add(table);
            doc.Close();
        }
        catch (Exception ex)
        {
            MessageBox.Show(ex.Message + "\r\n" + ex.StackTrace, "Error Generating PDF", MessageBoxButtons.OK, MessageBoxIcon.Error);
        }
    }

I'm guessing my problem has to do with setting column widths, but I'm not sure. One time, and only one time..I saw an error when I tried to open the PDF that said "illegal floating point division by 0" or something along those lines.

Any help is greatly appreciated.