AI not being positioned onto spline when using Blackboard and Behavior Tree

Hi, I’m trying to get a racing AI to follow a spline using blackboard and behaviour trees. I’ve posted this in the answerhub nearly a month ago but alas nothing, so I thought I’d try here.

I’ve got my AI_Racer, AI_Racer_Controller, AI_Racer_Blackboard and AI_Racer_BehaviorTree. Along with a BTTask, BTT_FollowRacingLine with the position onto spline information. I’ve got a BTTService which checks that the race has started (defaulted to Yes)

Anyway I’m trying to position the car onto the spline and I’m using the BP that works if placed straight in the Racer_AI BP, however when I put it in the BTTask it is ignored. The Behavior Tree is running and firing the FollowRacingLine node.

Anyway I put in breakpoints and noticed on the Cast To I’m greeted with this warning:

Warning: Looks like a wire-trace was not injected before the jump from ‘Cast To AI_Racer’ to ‘Cast To RacingLine’.

I’ve tried deleting the nodes and wires, even redone the BP in a new fresh BP. Still get the warning. I’ve put a print string after the first Cast To and that is displayed, though not after the Cast To Racing Line, which could be down to it not getting the key FollowRacingLine for the Get Blackboard Value as Object in the BTTask.

Can anyone point me in the right direction please?