WordPress MU

We have a new WPMU install (1.2.1), and have installed a new theme for one of the blogs. The theme is roughly based on the theme "Greeny", from http://sp.webarea.ro.

In any event, it seems as if the comments.php from the default theme is being used, rather than the comments.php in the theme we've set for the blog. I tried adding a comment (<!-- This is default -->) in the comments.php in the default theme, and it shows up when I load a page.

Is this normal? Is there something I can do to "fix" this? Is it likely due to the theme not being compatible with WPMU?

Is the theme's comments.php file reading by the webserver?

try setting the comments.php file permissions to 644 (rw-r--r--).

All of the files in the theme are world readable, and all the other theme files are being read just fine; they're currently 664 not 644 (though I tried setting to 644 just now just to make extra sure that wasn't the problem).

Any other ideas?

DId you compare the content of that theme's comments.php with the default theme to make sure they aren't actually the same?

That's irrelevant (though I did compare them and they're different) - because when I EDIT the default theme's comments.php, the changes show up, and when I edit the one in the theme they don't.

Have you tried clearing your browser cache?