Preblema registrazioni nuovi utenti

Salve, ho un problema sulle nuove registrazioni, porta un errore

ho lanciato la query ma il problema persiste. Cosa posso fare per risolvere?

Grazie.

query

ALTER TABLE `phpbb_confirm` ADD `davec_result` CHAR( 6 ) NOT NULL;

errore

Could not insert data into users table

DEBUG MODE

INSERT INTO phpbb_users (user_registered_ip, user_registered_hostname, user_id, username, user_regdate, user_password, user_email, user_icq, user_website, user_occ, user_from, user_from_flag, user_interests, user_phone, user_selfdes, user_profile_view_popup, user_sig, user_avatar, user_avatar_type, user_viewemail, user_upi2db_which_system, user_upi2db_new_word, user_upi2db_edit_word, user_upi2db_unread_color, user_aim, user_yim, user_msnm, user_skype, user_attachsig, user_allowsmile, user_showavatars, user_showsignatures, user_allowswearywords, user_allowhtml, user_allowbbcode, user_allow_pm_in, user_allow_mass_email, user_allow_viewonline, user_notify, user_notify_pm, user_popup_pm, user_timezone, user_time_mode, user_dst_time_lag, user_dateformat, user_posts_per_page, user_topics_per_page, user_hot_threshold, user_lang, user_style, user_gender, user_level, user_allow_pm, user_birthday, user_birthday_y, user_birthday_m, user_birthday_d, user_next_birthday_greeting, user_active, user_actkey) VALUES 
Line : 1131
File : usercp_register.php

Grazie lo stesso!