XF 1.1 Can't seem to get thread ID via $threadId

I'm quite confused of thi
What is the correct variable to use to output the thread ID? Trying to use it in the template ad_thread_view_above_messages

This does not work:

How can I show content in a specific thread?
<xen:if is="{$threadId} == x">
This content will show in thread x

Via: http://xenforo.com/community/resources/conditional-statements.1604/
<xen:if is="{$threadId} == 'x'">
You might have forgotten the apostrophe between the x value