Configuration check warning:
The locale is set to en_US, but this locale is not installed on this web server. Please either install the locale en_US or choose one of the installed locales for config.locale_all in your main template. Locales which are installed and therefore available are de_DE.utf8, en_US.utf8. If you intend to set another locale, you need to install it on this web server first.
When that is done, please empty the FE cache and reload this page.
The configuration check for this extension can be disabled in the extension manager.