Longtime Bernard Madoff assistant Annette Bongiorno on Monday testified that she had no idea her boss was operating a vast Ponzi scheme, despite the decades she spent helping run the trading business where it originated.Bongiorno said she recorded backdated trades, sometimes months after the fact, but never suspected there was anything illegal about it."Did anyone ever suggest to you that there was something wrong with that practice?" her lawyer, Roland Riopelle, asked her."The only person who ever suggested that to me was you," she replied.Bongiorno is on trial in Manhattan federal court along with four other Madoff employees, all accused of aiding the fraud.She became the second defendant to testify in her own defense, after Madoff's director of operations, Daniel Bonventre, chose to do the same last week. His testimony concluded on Monday morning.