[wp-hackers] checking for user logged in a plugin

[Chris McCoy]

Im doing this in a plugin

if(is_user_logged_in() && current_user_can('administrator')) {
        add_filter('stylesheet', 'admin_role_theme');
        add_filter('template', 'admin_role_theme');
}

But fires is_user_logged_in not defined, should I be firing this a diferent
way.

It basically selects the theme for admin only so he can work on a different
design live.