I inserted a link to the %author% output:

In %category% on %date('j. F , Y, #a#t g:i a')% by <a href="http://www.mtgeco.net/members/%author%/activity/">%author%</a>

It works, but i get all letters of the name capitalized "USER" and in addition without hover effect.

How do i fix this?

Look at the CSS being applied and see if it is being transformed

Thanks!
I just didn't note, that there are some boxes within atahualpa to alter the links in the kicker box. I removed those attributes and now its just fine!