Luxaeterna

Hello, I'm a french player so excuse me first for my bad english. I'm running the game on a Mac Book Pro retina 15" mi 2014, OS X 10.10.5 At the end of the quest "Master Below" when I killed the dragon hunter, after trying to put on her the amulet, the screen just turns black and I can't achieve the quest, neither do something else. I also tried to change the settings but without effects. Can you help me please? I'm blocked there! Regards, Luxaeterna