Changing Frontend Language in EasyBlog 5.07

I assume I am missing something, but I have set the Joomla 2.5. default language to German and have installed the German Language in the Language setting. It indicates "Language Installed" after pressing the Install/Update button and the list shows "German language installed". However, no change in the frontend. Also odd: if you purge the cache in the Languages settings, the previously installed language shows "Not Installed" again.
Any idea what is going wrong or what I am doing wrong?