Nostalrius Begins - Quality wow vanilla realm (1.12)

Hello, I'm working on this quest, and after killing the two waves that spawns after talking to Commander Gor'Shak, nothing happens. I had a message saying : "You don't meet the requirements ..." and the quest isn't even tagged -Failed-

I didn't started it myself though, I accepted when another player in the party took the quest.

Any suggestions ?

Same here, i don't have the -failed- tag but i can't turn the quest in, even if the 2 waves are dead. The npc won't react.
It worked for a member of my group thought.