Don't know where the problem lies, I have been trying to download files now from two different trackers with "login". I get the same error "Tracker status" Invalid answerer. I can't seem to get the exact response from the tracker anywhere.

Is this a known bug in ktorrent or is it some problem with both trackers?

I tried to download something from piratbay ant it was no problem. But login trackers don't seem to work at all.

Check out your log file (~/.kde/share/apps/ktorrent/log) and see if there's any usefull info about tracker error.