Как я могу решить, что ссылка на объект не установлена.

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я пытаюсь этот код вставить данные в таблицу, но у меня есть ошибка

Object reference not set to an instance of an object.

на

string id = cmd.Parameters["id"].Value.ToString();

мой полный код приведен ниже вместе с sql-кодом..

Что я уже пробовал:

таблица в sql.

create table addpinrequest(Appmstregno varchar(100), Qty varchar(100),Amount int, paymode varchar(100), [transaction] varchar(200), bankname varchar(200), branchname varchar(200), accountno varchar(200), ifsc varchar(100), [filename] varchar(200), msg varchar(200), id varchar(100)); 

хранимая процедура.

go 
alter procedure spaddpinrequest(@Appmstregno varchar(100), @Qty varchar(100), @Amount int, @paymode varchar(100), @transaction varchar(200), @Bankname varchar(200),@Branchname varchar(200),@Accountno varchar(200),@Ifsc varchar(100), @FileName varchar(200), @msg varchar(200),@id varchar(100))
as
begin
insert into addpinrequest(Appmstregno,Qty,Amount,paymode,[transaction], bankname,branchname,accountno,ifsc,[filename],msg,id) values(@Appmstregno,@Qty,@Amount,@paymode,@transaction,@Bankname,@Branchname,@Accountno,@Ifsc,@FileName,@msg,@id);
end

sp-код страницы в appcode.

public static string AddPinRequest = "spaddpinrequest";

код главной страницы.

protected void Button1_Click(object sender, EventArgs e)
   {
       if (datacheck())
       {
           int totalpackamount = Convert.ToInt32(((Label)gvPins.FooterRow.FindControl("lblTotalAmount")).Text);

           if (totalpackamount == Int32.Parse(txtAmount.Text))
           {
               string fileName = string.Empty;

               if (uploadFile.HasFile)
               {
                   fileName = "PAN/" + uploadFile.FileName;
                   uploadFile.SaveAs(Server.MapPath(fileName));
               }

               Int32 count = 0;
               DbCommand cmd = DataAccess.CreateCommand();
               cmd.CommandText = SP.AddPinRequest;

               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@Appmstregno", DbType.String, _master.UserMemberId));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@Qty", DbType.String, ((Label)gvPins.FooterRow.FindControl("Label1")).Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@Amount", DbType.Int32, txtAmount.Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@paymode", DbType.String, ddlPaymentMode.SelectedItem.Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@transaction", DbType.String, txtTransaction.Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@Bankname", DbType.String, txtBankName.Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@@Accountno", DbType.String, txtAccountNo.Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@Ifsc", DbType.String, txtIFSC.Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@FileName", DbType.String, fileName));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@msg", DbType.String, txtComment.Text));
               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "@Id", DbType.String, DBNull.Value, ParameterDirection.Output));

               int i = DataAccess.ExecuteNonQuery(cmd);
               string id = cmd.Parameters["@Id"].Value.ToString();

               if (i > 0)
               {
                   foreach (GridViewRow gr in gvPins.Rows)
                   {
                       if (gr.RowType == DataControlRowType.DataRow)
                       {
                           if (((CheckBox)gr.FindControl("chkSelectPin")).Checked)
                           {
                               cmd = DataAccess.CreateCommandText();
                               cmd.CommandText = "insert into PinDetail (RequestId, Qty, PlanName, TotalAmount, PlanId, Appmstregno) values (@RequestId, @Qty, @PinValue, @PinValue, @PlanId, @Appmstregno)";
                               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "PinValue", DbType.String, gr.Cells[2].Text));
                               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "PlanId", DbType.String, gr.Cells[1].Text));
                               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "Qty", DbType.String, ((TextBox)gr.FindControl("txtNoOfPins")).Text));
                               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "Appmstregno", DbType.String, _master.UserMemberId));
                               cmd.Parameters.Add(DataAccess.CreateParameter(cmd, "RequestId", DbType.String, id));

                               count += DataAccess.ExecuteNonQuery(cmd);
                               cmd.Parameters.Clear();
                           }
                       }
                   }
               }

               if (count > 0)
               {
                   reset();
                   Message.Show("Thanks, Request Send successfully. We will contact you soon..");
               }
               else
               {
                   Message.Show("Sorry!! There is something wrong please contact Administrator.");
               }
           }
           else
           {
               Message.Show("Sorry!!! Amount is less Then or Not equal to Total pin cost");
           }
       }
   }

<pre lang="c#">

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