I guessed I shouldn't just followed blindly. I followed the instruction in adding the following code to func.order.php but after removing it away, everything just work miraculously. Sorry to waste the space on this post.
$_fields = array_keys($default_address_book_fields);
foreach (array('b_', 's_') as $p) {
foreach ($_fields as $k) {
if($k!='address_2') {
$f = $p . $k;
if (isset($userinfo[$f])) {
$insert_data[$f] = addslashes($userinfo[$f]);
}
}
}
}