threadid conditional - Not working the same?

[kall]

Scenario: I want to display ads on all showthread pages (preferably in postbit), with specific ads for specific threads, and general ads for the rest.

In vB3, this was a matter of using this code wherever the ad was, and it would replace the generic ad with the specified one.

PHP Code:

<if condition="$thread['threadid'] == '12345'">Specific Ad for Thread #12345
<else/>
Generic Ad
</if> 


Now, using the new syntax below, the threadid condition is never true, no matter what template I stick it in:

PHP Code:

<vb:if condition="$thread['threadid'] == '12345'">Specific Ad for Thread #12345
<vb:else/>
Generic Ad
</vb:if> 


I've tried $thread['threadid'], $threadinfo['threadid'], $post['threadid'], and all without the '' inside the []. I'm beginning to lose it. Please help.