He found out he had been re-selected in the England team for its trip to South Africa but would have to serve an extra week of suspension.
Haskell was issued a three-week ban after punching Cheetahs forward Justin Downey in a match on April 28.
But that was extended to four weeks yesterday after it was found he did not have a clean disciplinary record.
The starting point for punishment for the punch was six weeks but was cut in half because of Haskell's clean record and admission of guilt.
However, Haskell had been banned for a week in 2008 after a club match, and that was brought to Sanzar's attention.
The judicial hearing was reconvened and Haskell explained he had completely overlooked the previous matter, and apologised.
Haskell and his counsel attended a further hearing before judicial officer Mike Heron and gave him a copy of the 2008 decision.
Heron ruled not as much weight could be given to a good disciplinary record and said the final penalty would be four weeks.
Haskell will now be available for only one match, against the Crusaders in Christchurch on June 1, before he travels to play for England in South Africa.
He will miss the match against the Blues at Eden Park on May 26, as well as the next two games, against the Hurricanes and Bulls.
Haskell (27), who last played for England at the World Cup, will join the squad in South Africa straight from New Zealand.
The three-test tour starts on June 9, with the final test on June 23. There are also two midweek games.
Highlanders high performance manager Greg O'Brien said the Highlanders always knew Haskell could go to South Africa and, under IRB regulations, he had to be released.
Meanwhile, Wellington flanker Scott Fuglistaller will join the Highlanders on Monday.
He will cover the openside flanker position after injury and suspension wiped out John Hardie, Doug Tietjens and Haskell.
Fuglistaller (25) was coached by Joseph and was a member of this year's Hurricanes wider training squad.
Hale T-Pole will be released from the squad.