Ink sacs are not yet obtainable in Survival mode. Because of this 2 light gray dye recipes, 1 gray dye recipe, 2 cocoa bean recipes, a 1 brown wool recipe are all unobtainable, yet they still appear in the crafting table list.
MCPE-6243
Unobtainable Crafting Recipes
Resolved
Works As Intended
1
(Unassigned)
Unconfirmed
Tablet - Android - Amazon Kindle Fire HD
crafting, dye, ink-sac
0.8.0 beta build 4
Retrieved
Not a bug, it just work as intended
UPDATE: Will be removed in 0.8.x, check out this:http://es.reddit.com/r/MCPE/comments/1srjll/how_to_obtain_ink_sacks_in_survival/ce0qaw3?context=3