asp.net mvc c# sqkbulkcopy No Value given for one or more required parameter

i am having this error No Value given for one or more required parameter

what might be the reason for the error. here is the code

  string excelConnectionString = @"Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + postdir + newFileNameOnServer + "; Extended Properties=Excel 8.0";


         using (OleDbConnection connection =new OleDbConnection(excelConnectionString))
         {
             OleDbCommand command = new OleDbCommand("Select Month,Year,CountryofExport,CountryofOrigin,Hs_code,quantity,Unit,CustomValue,Type FROM [qryTradeFlowforWeb$]", connection);
             connection.Open();

         // Create DbDataReader to Data Worksheet
       开发者_运维知识库    using (DbDataReader dr = command.ExecuteReader())   // the error coming here
           {
               string sqlConnectionString = ConfigurationManager.ConnectionStrings["KMFConnectionString"].ToString();
               SqlConnection conn = new SqlConnection(sqlConnectionString);
              using (SqlBulkCopy bulkCopy =  new SqlBulkCopy(sqlConnectionString))
              {
                bulkCopy.DestinationTableName = "ExcelData";
                bulkCopy.WriteToServer(dr);
              }
           }
      }

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Compare the destinatin table clolum list is identical with the source table column list. if not map the source and destination colum details using

bulkCopy.ColumnMappings.Add("SourceCol", "DestinationCol1");
bulkCopy.ColumnMappings.Add("SourceCo2", "DestinationCol2");
bulkCopy.ColumnMappings.Add("SourceCo3", "DestinationCol3");