WordPress MU

i have the following code in my single.php file.

<div class="post_info">This post was puplished on <strong><?php the_time('j. F Y') ?> at <?php the_time() ?></strong> in the category <?php the_category(', ') ?> by <a href="index.php?author=<?php the_author_ID(); ?>"><?php the_author_nickname(); ?></a>.</div>

somehow if i click on my author link i don't get redirected to the author archive. if i click the category link i get redirected to it.

if i click the author-link i don't get redirected to
http://myblog.com/subblog/author/admin/
instead the adressbar changes to
http://myblog.com/subblog/2009/08/29/testpost-in-the-subblog/?author=1

the weird thing is that if i click on the author-link one level above (index.php where all posts get shown) the link works.
i normally get to http://myblog.com/subblog/author/admin/

any ideas?

by "><?php the_author_nickname(); ?>

Change above to <?php the_author_posts_link(); ?> This displays a link to all posts by an author whereby the text link is the User's "Display Name" in his/her profile.

thank you!