Although you know the current TUG member password, you entered the old one in your profile when you registered for the new BBS today. If that's the one you are using, it's not the one that's been in effect since last November.
Also, if you correct the password in your profile, you'll show up in your posts as a TUG Member, not as a Guest - as you currently do.
If you still have problems, you might want to utilize the TUG password help form at this link -
http://www.tug2.net/passwordhelp.htm