Cant Go Forward In "acquiring Credentials"

I'm at the part where your quest book tells you to "Sneak around the guards in the darkness, and find a way into the vault". So I made my way past the guards and then did the puzzle that opens the vault. After entering the vault I got the document and then when I tried to exit into the coal blocks it tells me "You should not be entering here yet..." And when looking at my quest book it says the same thing. How do I fix this?