Graeme Smith has his doubts about the referral system
South Africa captain Graeme Smith says he has little faith in the umpire referral system.
The International Cricket Council [ICC] is to assess the controversial new system in May.
And Smith said: "I don't have a lot of confidence in it at the moment. Wrong decisions were made using it. It needs to be more conclusive."
But Australia skipper Ricky Ponting said: "It's not perfect, but the idea is to eradicate really bad decisions."
Referrals were introduced last year in the series between Sri Lanka and India. A batsman or bowler could appeal against the umpire's decision and a television official, also from the ICC's elite panel, would adjudicate.
England's first experience of it has come during the series in the West Indies, while it has also been used for Australia's tour of South Africa.
Two challenges are allowed per innings but while the TV official uses pictures and some of the Hawkeye technology, the part where the computer predicts where the ball is going is not used.
Smith, whose side were beaten by 162 runs by Australia in Johannesburg on Monday, added: "You've got to have all the technology available to make it work. If you're only using the technology in a half-hearted way you're going to increase the frustration."
ICC general manager Dave Richardson said referrals in cricket were more complicated than in other sports, such as tennis, where it was a simple matter of fact whether a ball was in or out.
"In the trials, we found the correct decision went up from 93 to 98 per cent," said Richardson. "If we are going for 100 per cent, we are fooling ourselves.
"We don't want the umpires to become coat hangers and ball counters. They must be able to show their skills. But often umpiring controversies cause bad blood among players. We found in the trial that there was no dissent and players were very happy."