Muhammad Rizwan PHP on "Fatal error: Call to undefined function is_user_logged_in()"

Hi there,

I am developing a Wp Plugin. While using wp_insert_post I got this error:

Fatal error: Call to undefined function is_user_logged_in() in /home/designs/public_html/WP/wp-includes/post.php on line 2185

Here is the file on pastebin: http://pastebin.com/YETGT4dK This file is included in main plugin file. See from line 93

Thank you !