How to make a tool automatically plant a crop?

So, I have a procedure, that is meant to check for when you right click a block, if that block is Dirt, Grass, or Farmland, it will either turn it into farmland or leave it alone, then it will plant either carrots or wheat. Only issue is, that when it tries to plant the seed, it just doesn't do anything. Can anyone help out?

Procedure (Shortened bcuz long script):
 

If [block at position x y z] = Grass_Block
do replace block at x y z with Farmland
     set local random = random(0, 1)
     if random = 0
     do place wheat at x y + 1 z
     else if random = 1
     do place carrots at x y + 1 z