integration with existing website problem

i installed wordpress under the folder root/blog/ in my existing website ftp.

i added ‘require(‘blog/wp-blog-header.php’);’ in root/index.php as instructed for existing website integration, but when i try to use wordpress functions such as is_user_logged_in() in root/index.php, nothing is returned.

when i echo is_user_logged_in(), nothing is printed out on the website

i want my existing website to be able to determine whether a user is logged in or not