You do use your fas login to report bugs, there is nothing in the settings on my end that would keep you from logging in. I would check with infrastructure, if you are sure you are typing your username/password combo correctly.
Blarg.
To log into bugzilla.redhat.com, I *must* use my email address, but to log into Trac there, I *must not* use my email address - it requires my username, "beland". This is not very user-friendly, especially since there is no link to any registration page.
It also doesn't seem very nice to disallow anonymous bug reporting, but I guess that's a policy decision.
-B.