I want to seperate my Option-Page functions and functions.php.
Therefore i moved Option-Page functions to another file "includes/options.php".
Including the file with require_once("includes/options.php") does not work anymore (I am absolutely sure that it worked in past), but require_once("includes/options.inc") is working.
When should i use *.inc files and when *.php files?
Especially when theme or plugin developing.
I have done same as here: Organizing Code in your WordPress Theme's functions.php File?