can you give us an address? it might be a simple caching-problem with your browser, either in the front- or backend of your WP.
had the same problem myself and only found out by chance: the function only returns a value so you have to output it yourself:
<?php echo get_category_feed_link('78',''); ?>
that should do the trick, good luck!
I just replaced the updated files from the TRAC system and it’s working like a charm right now. If you want to download a ready to install ZIP-file, I put one up on my site: http://www.uni-giessen.de/demokratische-linke/termine/wp-slimstat-ex-plugin-v161/
As far as I can see, I included all changes in the version 1.61. If you find anything awry, please let me know here or on my blog.
