Default text to display in every first post

[donkspurs]

I'm trying to display some text which will show in every first post in every thread, but I also only want it to display in a specific forum section. The id of the forum is definitely 22 and I've already found some code which apparently should work.

Here is the code I am currently using in the template "ad_showthread_firstpost_start".

<vb:if condition="$forum[forumid] == 22">

This is the custom text.

</vb:if>

However for some reason this text doesn't display at all in the threads in the specified forum.

If I remove the if condition then the text displays fine, but it obviously then displays in every single thread on the site.

I am testing this on a dev forum so the forums are turned off. I can't see that being an issue but thought worth mentioning in case.

Any help would be much appreciated! Thanks.