I create a simple plugin with this structure:

plugins/myplugin/
                 myplugin.php
                 parts/meta-boxes/
                                  mybox.php

Those files are pretty simple, I define one custom post type and mybox.php adds one meta box with a simple field in there.
The file mybox.php never gets loaded despite several hours of tinkering and re-reading the documentation, the content of the file is correct and should load on the same post-type as the one defined in myplugin.php.

BUT when i move my meta-boxes folder into the main piklist plugin parts/ folder (plugins/piklist/parts), mybox.php gets read and I can see my meta box in my custom post type (=> the content of mybox.php is not the problem).

It looks like piklist doesn’t access the “parts” folder of my plugin and instead looks into its own folder.
I’ve triple checked the folder permissions for everything : the server is able to access the subfolders of my plugin.
My web server is apache2 on Linux.

I’ve had the same problem with stable piklist (0.7) and latest beta 2 release.