While I’ve played with textpattern at sharecode, I faced this issue that may come in touch with those who uses textpattern.
I was frightened with the fact that commenting support in articles which were written too long ago was expired. I’ve searched over all of the preferences - nothing about this - but it is almost obvious that it must be. The good thing is that I’ve googled and found the post, and through its comments I’ve reached the FAQ article.
The mean is if in your Admin -> Preferences -> Basic page for Comments section you see only two points (and you have 4.0.4 version and no wish/ossibility to update currently) – this article is for you.
You need to do just two actions. First - take ./textpattern/include/txp_prefs.php file from your hosting, find a 89 line:
$evt_list = safe_column('event', 'txp_prefs',
"type = 0 and prefs_id = 1 group by 'event' order by event desc");
and to delete the quotes wrapping event to make it match with this variant):
$evt_list = safe_column('event', 'txp_prefs',
"type = 0 and prefs_id = 1 group by event order by event desc");
second – redeploy the file back. Finita la comedia – you’re welcome in preferences, Comments:Disabled after.