If you type some string in Player name field (login form) and press submit button, the register form will display an error message (player name taken) even if that is not true.
Same here. When I type my username and password it says "Invalid username or password. Please try again!" (I am pretty sure I'm using a correct password) and at the same time it shows "This player name has already been registered." in the register form.
Also when I try to recover my password with my e-mail it says "E-mail address unknown.". Then I checked this by trying to register another account with that e-mail and it says e-mail already in use.
I have the same Problem! If I want to login with my Account it says that the Username or password are not correct(but I'm sure they are) and if I try to reset my password it says, that the e-mail adress can not be found....
When you registered on another market then beta, you adress (and username) are indeed unknown here. Please read the last answers in the topic linked above.