Required Fields in Registration page does not work

Hi
I've just discovered that if you have a registration page with some required fields, BUTyou do not have an ADD page for the table the fields depend, if you do not input ALL data in register page you get this error:
Itseems that you add duplicate key fields.
Please check data you enter on the ADD page.
Now in my project i use an employer table with some fields (name, surname, sity, e-mail etc) BUT i do not have an add page becuse user can see only his own data (security setting).In registration page I use some REQUIRED FIELDS (username, password, surname, city) but if user trying to register does not edit this fields, I have the error described before.
How can I solve this problem?
As usual, any help appreciated.