Android MotionLayout: MotionScene not triggered

Question

I built a very simple example using MotionLayout, but for some reason the onClick does not trigger the animation.

What am I missing??

I have the following layout:

<androidx.constraintlayout.motion.widget.MotionLayout
    android:layout_height="match_parent"
    android:layout_width="match_parent"
    app:layoutDescription="@xml/scene_substitution"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    >

    <View
        android:id="@+id/animateMe"
        android:layout_width="50dp"
        android:layout_height="500dp"
        android:background="@android:color/holo_red_dark"
        app:layout_constraintTop_toTopOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        />

    <Button
        android:id="@+id/startAnimation"
        android:layout_height="wrap_content"
        android:layout_width="wrap_content"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        android:text="Click me"
        />
</androidx.constraintlayout.motion.widget.MotionLayout>

And the folloting scene description:

<?xml version="1.0" encoding="utf-8"?>
<MotionScene xmlns:motion="http://schemas.android.com/tools"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <Transition
        motion:constraintSetStart="@+id/start"
        motion:constraintSetEnd="@+id/end"
        motion:duration="1000">

        <OnClick
            app:targetId="@+id/startAnimation"
            app:clickAction="toggle"
            />

    </Transition>

    <ConstraintSet android:id="@+id/start">
        <Constraint
            android:id="@+id/animateMe"
            android:layout_width="100dp"
            android:layout_height="400dp"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"

            android:background="@android:color/holo_blue_bright"
            />
    </ConstraintSet>

    <ConstraintSet android:id="@+id/end">
        <Constraint
            android:id="@+id/animateMe"
            android:layout_width="300dp"
            android:layout_height="100dp"
            app:layout_constraintTop_toTopOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintEnd_toEndOf="parent"

            android:background="@android:color/holo_green_dark"
            />
    </ConstraintSet>

</MotionScene>

Answer 1

Finally got it! I used the wrong namespace value for xmlns:motion.

It supposed to be xmlns:motion="http://schemas.android.com/apk/res-auto", of course...