Can't place something in the top of the furnace.

Hi !
I can't place something on the "top input" part of the furnace (don't know how to call it). And I have a raw chicken in my inventory but it's not display on the furnace inventory.
So it's kind of boring when I play on survival.

Thanks !

(And I can't find the 0.13.1 Alpha version I'm playing on)