Внешняя таблица не находится в ожидаемом формате в C#

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Мой код выглядит следующим образом

у меня есть одна кнопка под названием uploadFarmerData и выберите Файл и загрузите его.

для этого кода выполните следующие действия

if (e.CommandName == "UploadFarmerData")
{
пробовать
{

строка CurrentFilePath = Path.GetFullPath(FileUpload1.PostedFile.имя файла);
Econ = new OleDbConnection(constr);
Экономический.Открыть();
Объект DataTable dtExcelSchema;
dtExcelSchema = кандидат экономических наук.GetOleDbSchemaTable(OleDbSchemaGuid.Таблицы, null);
строки листа = dtExcelSchema.Строки[0]["ИМЯ_ТАБЛИЦЫ"].Метод toString();
DataSet ds = новый набор данных();
строки листа = dtExcelSchema.Строки[0]["ИМЯ_ТАБЛИЦЫ"].Метод toString();
строка sql = "SELECT * From [" + SheetName + "]";
OleDbDataAdapter da = новый OleDbDataAdapter();
Объект oledbcommand cmdExcel = новый объект oledbcommand(среда SQL, кандидат экономических наук);

 da.SelectCommand = cmdExcel;
                        da.Fill(ds);
                        Econ.Close();
                        DataTable dt = new DataTable();
                        dt = ds.Tables[0];
                        bool s = false;
                        if (dt.Rows.Count > 0)
                        {
                            for (int i = 0; i < dt.Rows.Count; i++)
                            {
                               string firstname = dt.Rows[i]["farmername"].ToString();
                                string lastname = "";
                                string surname = "";
 string[] nameSplit = firstname.Split(new string[] { " " }, StringSplitOptions.None);
                                if (nameSplit.Length == 2)
                                {
                                    firstname = nameSplit[0].ToString().Trim();
                                    lastname = nameSplit[1].ToString().Trim();
                                }
                            }
                        }

                          s = true;
                          if (s)
                            {
                 showStatusTrue.InnerHtml = "Farmer Details Uploaded Successfully";
                            }

                           else
                            {
                 showStatusFalse.InnerHtml = "Farmer Details Uploaded Failed";
                            }
               catch (Exception ex)
                    {
                         showStatusFalse.InnerHtml = "Farmer Details Uploaded Failed";
                    }
              }
          }


 i have one button called uploadFarmerData and select the file and upload, when i upload shows error as follows

            External table is not in the expected format

  please let me know what is the mistake in my above code.

What I have tried:

My code as follows

  if (e.CommandName == "UploadFarmerData")
                {
             try
                 {

        string CurrentFilePath = Path.GetFullPath(FileUpload1.PostedFile.FileName); 
       Econ = new OleDbConnection(constr);
       Econ.Open();
      DataTable dtExcelSchema;
      dtExcelSchema = Econ.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);
      string sheetName = dtExcelSchema.Rows[0]["TABLE_NAME"].ToString();
      DataSet ds = new DataSet();
      string SheetName = dtExcelSchema.Rows[0]["TABLE_NAME"].ToString();
      string sql = "SELECT * From [" + SheetName + "]";
      OleDbDataAdapter da = new OleDbDataAdapter();
      OleDbCommand cmdExcel = new OleDbCommand(sql, Econ);
      <pre> da.SelectCommand = cmdExcel;
                        da.Fill(ds);
                        Econ.Close();
                        DataTable dt = new DataTable();
                        dt = ds.Tables[0];
                        bool s = false;
                        if (dt.Rows.Count > 0)
                        {
                            for (int i = 0; i < dt.Rows.Count; i++)
                            {
                               string firstname = dt.Rows[i]["farmername"].ToString();
                                string lastname = "";
                                string surname = "";
 string[] nameSplit = firstname.Split(new string[] { " " }, StringSplitOptions.None);
                                if (nameSplit.Length == 2)
                                {
                                    firstname = nameSplit[0].ToString().Trim();
                                    lastname = nameSplit[1].ToString().Trim();
                                }
                            }
                        }

                          s = true;
                          if (s)
                            {
                 showStatusTrue.InnerHtml = "Farmer Details Uploaded Successfully";
                            }

                           else
                            {
                 showStatusFalse.InnerHtml = "Farmer Details Uploaded Failed";
                            }
               catch (Exception ex)
                    {
                         showStatusFalse.InnerHtml = "Farmer Details Uploaded Failed";
                    }
              }
          }


 i have one button called uploadFarmerData and select the file and upload, when i upload shows error as follows

            External table is not in the expected format

  please let me know what is the mistake in my above code.

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