I don't have a Kindle 4, but several users reported issues with the dictionary lookup feature, which might be limited to the 6 officially supported Kindle languages (English, French, Italian, German, Spanish and Portuguese).
If that is indeed the case, you might have to add the ASIN number of a default dictionary that you don't use, e.g. B005EOCESI for Portuguese, to your custom dictionary. (You'll also have to change the language code of your Norwegian books to Portuguese). For more information see this
related thread.
Another possibility is that the Kindle 4 supports only Unicode dictionaries. In that case changing the following line might work:
Code:
<output encoding="Windows-1252" flatten-dynamic-dir="yes"/>
<output encoding="utf-8" flatten-dynamic-dir="yes"/>
However, I don't think that it'll make a difference, but it couldn't hurt to give it a try.