"Not in the morning, but in the afternoon."
Translation:Nem reggel hanem délután.
Why "nem a reggelt, hanem a délután" is wrong? the "in the" is lost in this case why?
In your answer you have turned both the time expressions into nouns by prefixing them with 'a'. Additionally you have ended 'reggel' with a 't', turning it into an object. The sense of "in the" is within the time expressions 'reggel' and 'délután', it doesn't get lost.