Dear Andres R,
Yes, these commands are in the installation manual.
sudo chmod 775 -R your_redmine_root_folder
sudo chown -R your_web_server_group:your_web_server_user your_redmine_folder
rake redmine:plugins:migrate RAILS_ENV=production
sudo service apache2 restart
Custom Menu plugin is working at plugins menu, but it can't change my Redmine's view.
So I think the trouble has occurred due to authority.
Thank you for your cooperation.