Flexi Auth, $this->flexi_auth->insert_user() shows “Creating default object from empty value” error

[eluser]Unknown[/eluser]
I'm starting with Flex Auth in CodeIgniter, and I should missed or misunderstood something.

Any idea why this piece of code is giving an "Creating default object from empty value" error ?

My code :

Code:

$this->load->library('flexi_auth');

$email = '[email protected]';
$username = 'nils';
$password = 'nilsnils';
$user_data = '';
$group_id = 1;
$activate = TRUE;

$this->flexi_auth->insert_user($email, $username, $password, $user_data, $group_id, $activate);
exit();

An other try with FALSE for $user_data :

Code:

$this->flexi_auth->insert_user($email, $username, $password, FALSE, $group_id, $activate);

Gives the same error.

User is added to database. But there is this error on the page :

Code:

A PHP Error was encountered
Severity: Warning
Message: Creating default object from empty value
Filename: models/flexi_auth_lite_model.php
Line Number: 47

This is the models/flexi_auth_lite_model.php line 47 :

Code:

$this->auth->session_name = $this->config->item('sessions','flexi_auth');

I did not found something on internet I could understand with "flexi_auth->insert_user" and "Creating default object from empty value".

Thanks for help. Nils.