There are two issues that may be causing you difficulty. The first is that I need to approve new members. This is because the site uses the most common forum software and there are "programs" called bots that simulate new users, register, then post endless amounts of spam. I'm looking for ways to defeat that without having to approve everyone.
The second is that people use their browsers password software. When they register they save their password as associated with their email registration. However, this forum uses your username to login. Therefore you must try again with your username, then re-save when prompted by your password software for ease in the future.