Why BuddyPress fields not saving?

The user_register hook probably fires too early.

Try:

add_action( 'bp_core_signup_user', 'auto_login_new_user', 100, 1 );

$user_id is passed by the bp_core_signup_user hook.

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)