$_COOKIE empty within included wordpress page

hello,

i’ve (for me) strange phenomena regarding cookies not beaing readable within a wordpress page getting included from a non-wordpress app running on the same server.

aim:
what i wanna do is listing wordpress categories within the sidebar of another application running on the same server. to do so i created a wordpress page, assigned a custom template to it, which reads the wordpress categories and prints them out in html. then i include this page from another application running on the same server. that works fine.

problem:
but now i installed the ac_authenticator.php plugin to have the wordpress blog accessible for registered users only. and after doing so the included wordpress page doesn’t seem to recognize the set cookies and so i get redirected to the wordpress login page.
$_COOKIE is just an empty array for the ac_authenticator.php plugin when it gets called from the included wordpress page.
(i also installed the root-wp-cookie cookie to have cookies valid for the whole server and not only for the /blog/ directory.)

does anybody have any idea, why the $_COOKIE array is empty within ac_authenticator.php getting called from the included wordpress page?

code:
from the externall app i include a wordpress page:
include(‘../blog/?page_id=7’);

as far as i don’t use ac_authenticator.php that works just fine, but with the plugin activated, this include redirects me to the wp-login page as ac_authenticator.php receives $_COOKIE being empty.

if i add a print_r just a line after (or before) having included the wordpress page, the $_COOKIE works fine and is filled with the wordpress_user etc. cookies.
include(‘../blog/?page_id=7’);
print_r($_COOKIE);

so why for the included wordpress page resp. ac_authenticator $_COOKIE is empty?!

bests,
fabian