php warning

i am getting this error log:
PHP Warning: array_multisort() [function.array-multisort]: Argument #1 is expected to be an array or a sort flag in /home/xxxxx/public_html/wp-content/plugins/leaguemanager/lib/shortcodes.php on line 277

this is the line 277:
if ($time==’prev1′){ array_multisort( $matchdate, SORT_ASC, $matches ); }
thanks for help.

http://ww.wp.xz.cn/plugins/leaguemanager/