12 X 2 High. = 24 Bookshelves
The Bookshelves need to "face" the Enchantment Table which should be standing on the floor. The 4 X 2 in the corners is useless.
A third row on top dosn't do anything.
Elevating the Enchantment Table 1 blok dosn't do anything. The "Rays" can't go downwards.
Access from underneath (or from the top).
Pic. to be added later
Dude, you're responding to a half-year old post. It was changed in the last update.