XF 1.5 Adding {xen:if $category.hasNew, '{xen:phrase unread_messages}'} to parent

[Wyvh]

Greetings,
I'm trying to change the following part of the templates node_forum_level_2 and node_category_level_2 by adding the red part to them, so it would add the class "unread" to the selected div.. but it doesn't work.

<div class="node forum level_{$level} {xen:if '{$level} == 1 AND !{$renderedChildren}', 'groupNoChildren'} node_{$forum.node_id} {xen:if $category.hasNew, '{xenhrase unread_messages}'}" data-fname="{$forum.title}">

Any idea ?
Thanks.