Accessed None 'CallFunc_BreakhitResult_HitActor2'

I’ve been trying to get a simple detection system working that allows an AI controlled pawn to follow the player, exactly as its described in the Behavior Tree Tutorial.
However when I updated to 4.7 everything broke, and I replaced all the nodes that needed to be replaced.
Except that now its giving me this result after running in the editor (and the AI pawn running to a angled location before returning to its origin point as a blackboard key is invalid)

This is the blueprint itself, exactly as its supposed to be laid out:

And this is the debug view in the editor when it is running:

I’m stuck trying to figure out why this sphere trace is causing this error, as it is stopping the blueprint from assigning the player’s pawn to the TargetToFollow blackboard key, which stops the BT right from the start.
Anyone know why its doing this?
Using Unreal 4.7.3

All the error message says is that you’re trying to use null value (or None) to do something, like calling a function (no idea what you do with it, it’s just outside of the AgroCheck screen you’ve attached). That null value is the Hit Actor you get by breaking up the hit result. I suggest you used blueprint debugging tools (most notably breakpoints!) and debug that blueprint a bit.

Cheers,

–mieszko