[Koha] another Koha 2.2.0RC4 question

It's imposible to me add a member. Is the "zipcode" field mandatory we don't use it here in Chile (as I know), Do i have to set something in the parameters before adding new members? I only get the error page but no error cause displayed. Another thing... why with the Spanish translation the pages seems different? only text displayed in the pages and no background color. Ok hope someone could help with the first issue it is more important to me... Thanks Cheers J0sep