Modifying MaxWalkSpeed using a Timeline

I’m trying to use a timeline to lerp my MaxWalkSpeed float to form acceleration/deceleration.

As you can see, I’m attempting to use a MapRangeClamped node to produce a point along my timeline (the timeline is 3 seconds long) and then to either reverse or play based on whether the character needs to accelerate or decelerate.

Am I missing soemthing obvious here? The current behaviour never seems to apply the correct NewTime.

I’ve kinda cheated in the end, by using two timelines. Doesn’t work as sweet as I though the other method might, but it’ll do for now.