http://www.perlmonks.org?node_id=727275


in reply to Hash of arrays

This might sound silly, but try adding a few print statements around the line that is causing you trouble. e.g. 
  print( STDERR "key is \"$key\"\n" );
  print( STDERR "t is \"$t\"\n" );

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Run again and see if that brings up any obvious issues.

In Section Seekers of Perl Wisdom