It isn't wrong, it's an accepted answer. The incubator tells me that the sentence was last changed two years ago but there's no way of telling what might have happened in your specific case. Could have some other typo or just a temporary glitch.
Great question. I was consulting my other Swedish literary scholars and realized that I have no idea how to construct Swedish sentences because I am learning the language on DUO and wanted to ask question so it can be answered by someone more experienced than me.