I can't spare SIlus in the Mehrunes Razor quest?

No matter what i do, after Dagon finishes talking SIlus becomes hostile right after. I even pick the "i wont kill him" dialogue option. But then Silus talks to me, forcibly turns me toward him and then he instantly interrupts himself or closes the dialogue on his own and becomes hostile. I've seen a video how its supposed to go. I never get to talk to him to say i wont kill him. He instantly interrupts himself and becomes hostile, I've reloaded like 3 times but its the same thing everytime. Is there someway to fix this? Maybe a console command? The first thing i thought of is a calm spell but im not a mage