I've been working with WP for quite a while now however I was never required to use translations for it - until yesterday happened.
I'm currently using the Plugin 'Theme My Login' to build a frontend interface for subscribers, which is supposed to be completely German. However, for some odd reason, about half of the error messages thrown are English and the other fifty percent are German. For example, after logging out of WordPress, the message telling you to 'log in to access this page' is german, while the login error messages (e.g. wrong password, non-existent user etc.) are english.
I've tried editing the standard WordPress language file de_DE to match my requirements as well as editing the language file that comes with the plugin, however none of the changes I make seem to have any effect on the actually displayed errors.
Could anyone of you imagine what mistake I keep making here?