Question SetOutputCount of Playable behaves not right, Help.

Here is my playable graph.
I have a CrossFadePlayableBehaviour(2). I need to do a crossfade effect of animation. The CrossFadePlayableBehaviour(2) has 2 output ports. I set port 0 connected to the animation mixer(3). I want the animation to blend with the previous Animation Output(default pose) with an avatar mask. The green Animation Script(6) does nothing, and it just stands for the previous Animation Output because I set the output of these nodes using the previous output as the default input. I set port 1 to Animation Mixer(4) which just passes the animation to the next node.
Here the animation layer mixer blends the two streams with a weight. But I find something not right.
I change the blend weight of AnimaitonLayerMixer(5), but I can see the result from AnimaitonLayerMixer(3) is blended with the default pose. If I connect port 0 of CrossFadePlayable(2) to AnimationLayerMixer(4) and connect port 1 to AnimationLayerMixer(3), then I can see that the result of AnimationLayerMixer(4) is blended with the default pose.


So I think the problem is that if I create two output ports from one playable, only one of them works. So I wonder how could I correctly connect 2 output ports of one playable to different animation mixers?