Ошибка при записи в ячейку.

SqlConnection thisConnection = new SqlConnection(@"Data Source=KING;Integrated Security=SSPI;Initial Catalog=master");
			thisConnection.Open();

			SqlDataAdapter thisAdapter = new SqlDataAdapter("SELECT WM,FIO from WebMoney", thisConnection);

			SqlCommandBuilder thisBuilder = new SqlCommandBuilder(thisAdapter);

			DataSet thisDataSet = new DataSet();
			
			thisAdapter.Fill(thisDataSet, "master");

			Console.WriteLine("NAME: {0}", thisDataSet.Tables["master"].Rows[0]["FIO"]);

			thisDataSet.Tables["master"].Rows[0]["FIO"] = "The test string!";
			thisAdapter.Update(thisDataSet, "master"); //ВОТ ТУТ ВЫВОДИТ ОШИБКУ

			Console.WriteLine("NEW NAME: {0}", thisDataSet.Tables["master"].Rows[0]["FIO"]);

			thisConnection.Close();