Grasping class / controllers

Hi all, I am using Codeigniter framework, tho' I believe my question is more PHP related in general. Problem I am having is following. Codeigniter (CI) uses general class CI_Controller for all functions. I have extended this controller with: abstract class CORE_Controller extends CI_Controller {...}. Then, I also have a RESTFul library which is: class Cpin2_rest {} And, last one is Ion Auth library which states: class Ion_auth {} In the Ion auth, there (should be) is initialization of CI_Controller with: $this->ci =& get_instance(); However, $this->ci inherits Cpin2_rest instead of CI_Controller (or CORE_Controller). I really have no idea where have I made a mistake and can't get around this one :( Any help is appreciated! Thanks! Aleks