使用NPOI，点击右键菜单生成报表，写入excel，出现异常。调试点了没反应，程序也没崩，也没停在哪个地方。

private void toolStripMenuItem5_Click(object sender, EventArgs e)
        {
            if (((TextBox) Controls.Find("textbox1", true)[0]).Text != null &&
                ((TextBox) Controls.Find("textbox2", true)[0]).Text != null &&
                ((TextBox) Controls.Find("textbox3", true)[0]).Text != null &&
                ((TextBox) Controls.Find("textbox4", true)[0]).Text != null &&
                ((TextBox) Controls.Find("textbox5", true)[0]).Text != null &&
                ((TextBox) Controls.Find("textbox6", true)[0]).Text != null )
            {
                string WriteExcelPath = @"../../工艺报表.xlsx";
                using (FileStream fs = new FileStream(WriteExcelPath, FileMode.Open, FileAccess.ReadWrite))
                {
                    IWorkbook  workbook = new XSSFWorkbook(fs);
                    ISheet sheet = workbook.GetSheet("sheet1");
                    IRow row = sheet.GetRow(1);
                    row.GetCell(0).SetCellValue(((TextBox) Controls.Find("textbox1", true)[0]).Text);
                    //MessageBox.Show(((TextBox) Controls.Find("textbox1", true)[0]).Text);
                    row.GetCell(1).SetCellValue(((TextBox) Controls.Find("textbox2", true)[0]).Text);
                    row.GetCell(2).SetCellValue(((TextBox) Controls.Find("textbox3", true)[0]).Text);
                    row.GetCell(3).SetCellValue(((TextBox) Controls.Find("textbox4", true)[0]).Text);
                    row.GetCell(4).SetCellValue(((TextBox) Controls.Find("textbox5", true)[0]).Text);
                    row.GetCell(5).SetCellValue(((TextBox) Controls.Find("textbox6", true)[0]).Text);
                    
                    //Exception of type System.InvalidOperationException was thrown
                    workbook.Write(fs);
                    //fs.Close();
                }
            }
        }

代码是按照官方示例写的啊

错误提示：