Hello everyone, I am trying to implement the following animation blending in a timeline using C#.

As you can see, the "start" animation is a 20-seconds-long animation and it is non-looping. The mix time is 2s. The "idle" animation is a looping animation, so here is my code:
TrackEntry Ani1 = AnimationState.SetAnimation(0, aimFirst, false);
Ani1.MixDuration = 2.0f;
AnimationState.AddAnimation(0, aimSecond, true, 0);
However, the code seems not working as the timeline result.