Translation:I need the soap, but I do not find it.
Well, that depends on your point of view. You really can if you tried harder. You would probably say "but I don't find it." if you are still looking for it. We are more likely to say either "I can't find it" or "I haven't found it yet." to make the difference more obvious, but right now we are not sure what will happen as we grope around the slippery floor. Is the cup half empty or half full?
I decided to translate this as "I need soap..." - even though the Esperanto includes "la" - because "I need the soap" sounds odd in English. It's possible, if you're talking about a specific soap, but not really common. So... should I report my version as something Duo should accept, or is there an Esperanto rule or habit I'm not aware of?