CI and tank_auth

[eluser]Unknown[/eluser]
Im just at installation phase, followed the tutorial on http://konyukhov.com/soft/tank_auth/


url: http://localhost:8888/CI/index.php/auth/login

basically im getting the following error.

An Error Was Encountered
Unable to load the requested class: security


-- using CodeIgniter2.0

all help is greatly appreaciated, many thanks...