Encontrei o erro.
Display.template.php
Procurar:
// Build the normal button array.
$normal_buttons = array(
'reply' => array('test' => 'can_reply', 'image' => 'reply.gif', 'lang' => true, 'url' => $scripturl . '?action=post;topic=' . $context['current_topic'] . '.' . $context['start'] . ';num_replies=' . $context['num_replies']),
Substituir:
// Build the normal button array.
$normal_buttons = array(
'reply' => array('test' => 'can_reply', 'text' => 146, 'image' => 'reply.gif', 'lang' => true, 'url' => $scripturl . '?action=post;topic=' . $context['current_topic'] . '.' . $context['start'] . ';num_replies=' . $context['num_replies']),
Estava difícil... -.-''