Unable to complete/attune "Ifrit Bleeds, We Can Kill It"

Unable to Attune the Zahar'ak Aetheryte.
I tried 40 times maybe. When i do it, It says: "Quest Completed", The duty Finder has been Updated... But nothing have happens.

Always same thing. It give me again possibility to Attune Aetherithe.

It is loop.

How can i do to continue my Main Story.

Thanks.

OK now it work. I had my inventary full.
But it didnt give me any item.
Bah! ok.... Thanks!