Ошибка при открытии Excel файла

void OpenExcel()
        {
            string file = @"Data\Timetable.xlsx";
 
            Excel1.Application ex = new Excel1.Application();
            ex.Visible = true;
            ex.DisplayAlerts = false;
            Excel1.Workbook book = ex.Workbooks.Open(file);
            //Excel.Workbook book = ex.Workbooks.Open(file, 0, true, 5, "", "", true, Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);
            //ex.Workbooks.Open(file, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing, Type.Missing);
 
            Excel1.Worksheet sheet = (Excel1.Worksheet)ex.Worksheets.get_Item(1);
 
            int rowExcel = 4;
 
            string date = textBox5.Text;
            sheet.Cells[1, 1] = "ЗАМЕНЫ НА " + date + "";
 
            for (int i = 0; i < dgv.Rows.Count; i++)
            {
                sheet.Cells[rowExcel, "A"] = dgv.Rows[i].Cells[0].Value;
                sheet.Cells[rowExcel, "B"] = dgv.Rows[i].Cells[1].Value;
                sheet.Cells[rowExcel, "C"] = dgv.Rows[i].Cells[2].Value;
                sheet.Cells[rowExcel, "D"] = dgv.Rows[i].Cells[3].Value;
 
                ++rowExcel;
            }

System.Diagnostics.Process.Start(@"Data\Timetable.xlsx");

Excel1.Workbook book = ex.Workbooks.Open(@"Data\Timetable.xlsx");