Can't get vanilla entity NBT tags

I am trying to make the player get bonus wool whenever they shear a sheep, and to do so I need to check the colour and state of the sheep using NBT tags (such tags are explained here). However, the procedure is not detecting these variables, and other testing showed that the variables are false and 0 (meaning it's not recognizing them). Thus, the bonus is always white wool and is given even when the sheep is already sheared.

How can I get the game to detect these variables properly so the bonus works as intended? 

Here's the block code: