Thank you for your reply. I think all files are in the right place with the right permissions. I checked this with my ftp-Programm:

/blog/wp-content/plugins/wp-juicebox/ (my blog is installed in a subfolder called "blog")

I reinstall an activate it, but i get the same Error-Message, when i try to add a gallery.

I have installed the plugin in Wordpress as described in the Manual to give your Plugin a try.

1.) There is no button to create a gallery in the Manage-Galleries Page. There are only "Delete all galleries", "set default", and "reset default" Buttons.  and there is also no  'Add Gallery' screen.  Do i miss something?

2.) Then i try to add a gallery via article, as described in the Manual. I opened the Editor, and clicked the "Add Juicebox Gallery" Button. An overlay-Dialog opened with the following Message:

Forbidden
You don't have permission to access /wp-content/plugins/wp-juicebox/jb-config.php on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.

? I have no idea to get it run ? I use WordPress 3.4.2.

Any Ideas?

Carsten