venin: I have the same problem. I solved the riddle on my own but I don't get ANY of the mouse prompts with exception to the book cases near Takeo. I watched some let's plays and it seems my game is bugged for some reason. I'll try a reload.
Got the solution:
Drop the book you get off of Takeo on the back table (where you can examine the book with the magnifying glass). Only then will you be able to pick up another book.
Just another thing that makes me unsure whether I like this game or not.... O_O