newDataRow.SetField("Cmd_MasterStandBy", MasterStandBy);>or thisnewDataRow["Cmd_MasterStandBy"] = (object)MasterStandBy ?? System.DBNull.Value;Thanks Rob, that worked! Now that you wrote it like that, I think I understand why it is needed, I was following an example found and I could not understand, nor make it work this dr["Application_Date"] = (...) ? (object)DateTime.Parse(...) : DBNull.Value;