Custom Dictionary on Kindle DX

[Bilter]

Hi all. First message to the forum. I've been using my Kindle DX for more than 10 years now, without any problems. For the last week, I have been trying to find and put some ready custom dictionaries (Ive tried this classic) and trying to create a customer dictionary myself, a German to English one.

Even though I followed the advice from many different threads on this forum as well as some other websites, I'm failing to make any of these dictionaries work on my Kindle. The mobi file is seen as a book by the Kindle, and when I open the book, I can search for words. But the lookup functionality which is so critical for me, is not working.

I suspect my Kindle version is simply too old, and the dictionary format has changed since so the given advice does not apply to me. I'm clutching at straws really. Can someone please help?