Next time your search engine results don't match your query try adding a + before the word. Otherwise DDG will include results that don't match your query (frustrating).
If it still doesn't work you can still use the + and also wrap your word in quotes (even though it is a single word).
Vise versa with - and removing words (also wrap in quotes if it doesn't work).
I don't know why DDG doesn't advertise this feature as some results are completely wrong without the +.