My Ultimate Facebook plugin did not want to leave people

Hello Guys!

My Ultimate Facebook plugin did not want to leave people to register for Facebook.

By clicking Register, one fills the two fields, title and adress, and confirm the following error appears:

Could not register such user

How to solve?

My site is http://www.lp-books.com.br/

PHP version is 5.4.17 my hosting

More information just ask.

I await your help.

Thank you!