Triden comments problem

I'm having a problem getting the comments template to show on pages in Triden. It shows fine on single posts, but I can't seem to get it to appear on (for example) category pages. Using 2.1, and can edit index.php or whatever is neceessary, but it seems to me like the correct code is there already.

As an example, if you look at this page
http://macaulay.cuny.edu/eportfolios/weinroth2009/category/historical-perspective/
there is not comments template--no place to leave comments or see comments.

But if you click on the post title and go to the single post page
http://macaulay.cuny.edu/eportfolios/weinroth2009/2009/08/26/hassam-images/
there it is, just as it should be.

Any ideas?