carpet stops bookshelves from powering up enchantment table.

I was putting the bottom layer of bookshelves in my enchanter and noticed that the table did not power up.

What I expected to happen was...:
I thought that carpet would not effect the enchantment table

What actually happened was...:
the carpet blocked the bookshelves from powering up the enchantment table.

Steps to Reproduce:
1. put carpet around the enchantment table