Type-o in your source!

Dear Wouter, first of all thanks for your plugin. We discovered a type-o which causes your plugin not to work ok.

In dd_roles.php you refer to three files. As you should you use .$plugin_url_path. (instead of the static wp-content). After that you use dd_roles to refer to your plugin but it should be dd-roles!

After changing that everything seems to work ok.

http://wordpress.org/plugins/dd-roles/