RSS – Opening and ending tag mismatch – WHY

I've been trying to debug my RSS feed with little success. I keep getting the same error, whatever I change in it.

"error on line 18 at column 61: Opening and ending tag mismatch: copyright line 0 and title"

You can view the feed here: http://www.dico2rue.com/feed.php

I've seen other posts, but they don't seem to answer my question, including:
Problem parsing RSS with a PHP script

Am I getting the CDATA wrong?

Any help much appreciated.