[Typo3] Front end user registration problem

[Piotr Burda]

I`ve instaled Front end user admin, and configured using tutorial from
http://typo3.hachmeister.org/Add_a_login.135.0.html

First page with form works, when i`m clicking on Create user, the second 
page opens with submitted info, everything is ok, but when clicking on 
Create user the third page opens with empty form and with error messages:
Invalid username.
There must be at least 4 characters in your username!
Invalid password ...etc

But all this info was entered correctly, where is the bug?

Piotr