[sloved]DB update error please help

[eluser]R_Nelson[/eluser]
i am not sure why this is not working

Code:

$id = $row->id;
                    $username = $row->username;                    
                    $data = array(
                             'activationkey' => '',
                             'user_level' => 1                            
                            );

                    $this->db->where('id', $id)->update('user', $data);
                    $this->account_active($username);

I am getting a DB error

A Database Error Occurred

Error Number: 1062

Duplicate entry '' for key 4

UPDATE `user` SET `activationkey` = '', `user_level` = 1 WHERE `id` = '3'

Filename: /home/content/62/7529062/html/Connect-my-friends/controllers/user.php

Line Number: 226

[eluser]R_Nelson[/eluser]
this was my mistake what i had was activactionkey set to unique in the DB so since one user was already set to '' it couldn't sent another one to that lol