Error inserting special characters (spanish) into database

[eluser]jorgeakanieves[/eluser]
Bufff...
I´m trying to insert special characters ( accent '´' and question character '¿' ) but the inserted field is null. If I do the query in phpmyadmin directly, it´s inserted all right.

I don´t know whay may be happening because I´ve defined:

database.php:

Code:

$db['default']['char_set'] = "utf8";
$db['default']['dbcollat'] = "utf8_general_ci";

And with the phpmyadmin client, my database, tables and fields are set to:
database: utf_spanish_ci
table: utf_spanish_ci
field: utf_spanish_ci

In the config file of mysql ( my.ini ):

Code:

[mysql]
default-character-set = utf8_general_ci
[mysqld]
default-character-set = utf8_general_ci
character-set-server = utf8
collation-server = utf8_general_ci
init_connect = 'SET collation_connection = utf8_general_ci'
init_connect = 'SET NAMES utf8_general_ci'

What´s the error?