"I am not the composer."
Translation:Nem én vagyok a zeneszerző.
I don't know if it's wrong. But adding én emphasizes that I am not the composer, which most closely matches the meaning of the English sentence I am not the composer (, someone else is the composer). Since you would never use this English sentence to mean anything else, I think it is only correct to emphasize én in the Hungarian sentence.
Well, you left out the definite article.
Besides that, I think your sentence is more like I am not a composer, but instead I am something else whereas Duo's sentence says It is not me who is the composer, but someone else is.
At least, this is my guess.
But do not despair, the word order is by far one of the most difficult things I find about Hungarian. It's not a trivial question.
the lack of the definite article makes it wrong, but also the word order given is preferred over your word order.
Also, the input system doesn't care about accent marks - it will point out the error, but it doesn't reject answers which are only wrong because of accent marks.
Oh, I should have realized the article myself. That's probably the most difficult thing in Hungarian at the moment as Finnish doesn't really have articles and then the confusion between Hungarian and English 'a'. So I either forget to use the article or choose the wrong one.
The English sentence is not the best here, or at least it's too ambiguous.
Nem én vagyok a zeneszerző. - It is not me who is the composer. I am not the composer. (but someone else)
Nem vagyok a zeneszerző. / Én nem vagyok a zeneszerző. - I am not the composer. (I have some other profession)