[RESOLVED] how to use session in my libraries?

[eluser]Unknown[/eluser]
i want to use session library in my own library, but i couldn't use it in my library.
i use this code:

Code:

$this->session->userdata('item');

i use it to check user is logged in. in my login class:

Code:

function loggedin($isadmin=FALSE) {
        //$this->load->library('session');
        if ($this->session->userdata('user_logged') == TRUE) {
            if ($isadmin)
                if ($this->session->userdata('user_isadmin') == FALSE) {
                    return FALSE;
                }
            return TRUE;
        }
        return FALSE;
    }