Bats aren't following players

I'm trying to make a custom mob that is a bat that follows a player until it is within 3 blocks. Then I want the bat to suicide and give the player a random potion effect. The problem is the bat won't follow the player for some reason, and it doesn't activate its skill whenever it's within range. This is my first time trying to mess around with skills like this... Any help would be appreciated.

The bat (aka Wisp) code:
http://pastebin.com/gzsT6GLk
The skill code:...

Bats aren't following players