I am having trouble splitting a plugin file into multiple pages. My index.php in the plugin directory works fine. Now I want to take a part of the code to a separate php file (details.php). But a hyperlink to details.php gives me the "You do not have sufficient permissions to access this page" error.
A direct link to this page gives me the same error. http://localhost:8888/wordpress/wp-admin/admin.php?page=myplugin/details.php
Do I have have to declare something?