Task: Question Answering
Input (English): Passage: Although the Arenafootball2 league played its tenth season in 2009, a conference call in December 2008 resulted in enough votes from owners and cooperation from the AFLPA for the AFL to suspend the entire 2009 season in order to create "a long-term plan to improve its economic model". In doing so, the AFL became the second sports league to cancel an entire season, after the National Hockey League cancelled the 2004-05 season because of a lockout. The AFL also became the third sports league to lose its postseason (the first being Major League Baseball, which lost its postseason in 1994 because of a strike). Efforts to reformat the league's business model were placed under the leadership of Columbus Destroyers owner Jim Renacci and interim commissioner Policy. Question: What led the National Hockey League to cancel the 2004-2005 season?
Output (English): a lockout