It works perfectly for me, don't know where could be the problem.
Try to log in and then go again to the index at this link:
http://kmeleon.sourceforge.net/bugs/index.php
and try again, if it still doesn't work try going directly to the bug report page at this link:
http://kmeleon.sourceforge.net/bugs/reportbug.php
If it still doesn't work you may have to wait until your account is activated or activate it through an e-mail you may have received (I don't remember the registration method, I registered long time ago) or something similar.
If nothing works I can send the bug report myself (but tomorrow, it's 2:00 AM in Spain and as KKO once said, tomorrow is a day too).