How to resolve required dependecies?

Okay so, i have problem with "Required Dependecies" in my code about itemstack, and i dont know a way to fix it, heres the code:

(remeber its not finished but i want to test out some of the part first before i expand)

Event trigger - Player left clicks block
IF item in entity's hand = wooden pickaxe
	deal the provided item damage of amount (1)
ELSE
	IF random[0,1) < 0,7
		add "dirt" to provided player inventory
	ELSE IF random[0,1) < 0,5
		add "sand" to provided player inventory
	ELSE
		add "gravel" to provided player inventory