Spoiler Apocrypha glitch?

[Ragnvaldr]

So I read the one black book in which you have to go through all the chapters and end up at the word wall with the last word in the Dragon Aspect shout. Get the word, try it out and then....nothing. How the hell do I get out of here?! I don't see another book, and the door is shut tight.

 

[MrDSL]

Read the black book from your inventory again. Its probably the last one needed to face Miraak.. You'll be glad you have that book out of the way. It will work after you kill Miraak.