Thank you, this solved the problem.
For some reason though, the extra fields are invisible, even if the HTML code is there. Please see:
http://www.blueneon.ro/alinush/hidden.jpg
Also, how can we insert these fields between the other address book fields? For example, I need Address line 3 after Address line 2, but I can't insert it there:
http://www.blueneon.ro/alinush/fields.jpg