preg_replace_callback() [<a href='function.preg-replace-callback'>function.preg-replace-callback</a>]: Requires argument 2, 'clean_pre', to be a valid callback" in file /var/www/red/engine/lib/input.php (line 158)

line 158 -->    $pee = preg_replace_callback('!(<pre.*?>)(.*?)</pre>!is', 'clean_pre', $pee );^