RTIR HTML not rendering

I’ve probably screwed up my RTIR install, but I’m hoping this is just
something stupid. The HTML (links and all) for RT 3.7.2 is working
wonderfully, but 3.7-EXPERIMENTAL-RTIR-2.2 isn’t actually rendering.
It’s displaying as code, a la:

email] [lookup
email] [lookup

Does anyone have any ideas as to what I could have done that would
have resulted in this little mishap?