无法设置CollapsingToolBarLayout

Question

我有一个CollapsingToolbarLayout试图设置为类似于列出的第一个示例here。

我已遵循我可以找到的所有说明和文档。以下是我的XML：

<android.support.design.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/draw_insets_frame_layout"
android:layout_width="match_parent"
android:layout_height="match_parent">

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


<android.support.design.widget.AppBarLayout
    android:id="@+id/appBar"
    android:layout_width="match_parent"
    android:layout_height="@dimen/barHeight"
    android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_scrollFlags="scroll|exitUntilCollapsed">

            <FrameLayout
                android:layout_width="match_parent"
                android:layout_height="wrap_content">

                <FrameLayout
                    android:id="@+id/photo_container"
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:background="@color/photo_placeholder">
                    <!--suppress AndroidLintContentDescription -->
                    <ImageView
                        android:id="@+id/toolbar_image"
                        android:layout_width="match_parent"
                        android:layout_height="match_parent"
                        android:scaleType="centerCrop"
                        android:fitsSystemWindows="true"/>
                    <View
                        android:layout_width="match_parent"
                        android:layout_height="112dp"
                        android:background="@drawable/photo_background_protection" />

                </FrameLayout>

                <com.example.xyzreader.ui.MaxWidthLinearLayout
                    android:layout_width="match_parent"
                    android:layout_height="wrap_content"
                    android:layout_gravity="center_horizontal"
                    android:layout_marginTop="@dimen/detail_card_top_margin"
                    android:background="#fff"
                    android:elevation="2dp"
                    android:maxWidth="@dimen/detail_card_max_width"
                    android:orientation="vertical">

                    <LinearLayout
                        android:id="@+id/meta_bar"
                        android:layout_width="match_parent"
                        android:layout_height="wrap_content"
                        android:layout_gravity="bottom"
                        android:layout_marginBottom="@dimen/detail_metabar_vert_padding"
                        android:background="#333"
                        android:orientation="vertical"
                        android:paddingBottom="@dimen/detail_metabar_vert_padding"
                        android:paddingLeft="@dimen/detail_inner_horiz_margin"
                        android:paddingRight="@dimen/detail_inner_horiz_margin"
                        android:paddingTop="@dimen/detail_metabar_vert_padding">

                        <TextView
                            android:id="@+id/article_title"
                            style="?android:attr/textAppearanceLarge"
                            android:layout_width="match_parent"
                            android:layout_height="wrap_content"
                            android:fontFamily="sans-serif-condensed"
                            android:lineSpacingMultiplier="0.9"
                            android:paddingBottom="@dimen/detail_metabar_title_bottom_padding"
                            android:textColor="#fff"
                            android:textSize="@dimen/detail_title_text_size"
                            android:textStyle="bold" />

                        <TextView
                            android:id="@+id/article_byline"
                            style="?android:attr/textAppearanceSmall"
                            android:layout_width="wrap_content"
                            android:layout_height="wrap_content"
                            android:textColor="#8fff" />
                    </LinearLayout>

                </com.example.xyzreader.ui.MaxWidthLinearLayout>
            </FrameLayout>

        <android.support.v7.widget.Toolbar
            android:id="@+id/main.toolbar"
            android:layout_width="match_parent"
            android:layout_height="?attr/actionBarSize"
            app:popupTheme="@style/ThemeOverlay.AppCompat.Light"
            app:layout_scrollFlags="scroll|enterAlways"
            app:layout_collapseMode="pin"
            />

    </android.support.design.widget.CollapsingToolbarLayout>


</android.support.design.widget.AppBarLayout>

<com.example.xyzreader.ui.ObservableScrollView
    android:id="@+id/scrollview"
    android:layout_width="match_parent"
    android:layout_height="match_parent">


<TextView
    android:id="@+id/article_body"
    style="?android:attr/textAppearanceMedium"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="@dimen/detail_inner_horiz_margin"
    android:layout_marginRight="@dimen/detail_inner_horiz_margin"
    android:lineSpacingMultiplier="@fraction/detail_body_line_spacing_multiplier"
    android:paddingBottom="@dimen/detail_body_bottom_margin"
    android:textColorLink="@color/theme_accent"
    android:textSize="@dimen/detail_body_text_size" />

</com.example.xyzreader.ui.ObservableScrollView>


</LinearLayout>

<android.support.design.widget.FloatingActionButton
    android:id="@+id/share_fab"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_marginBottom="@dimen/fab_margin"
    android:layout_marginRight="@dimen/fab_margin"
    android:background="@drawable/add_fab_background"
    android:contentDescription="@string/action_share"
    android:elevation="@dimen/fab_elevation"
    android:src="@drawable/ic_share"
    android:stateListAnimator="@anim/fab_state_list_anim"
    app:fabSize="normal"
    app:layout_anchor="@id/toolbar"
    app:layout_anchorGravity="bottom|end" />

很难描述这种行为，但是它不能正常运行。以下是图片，任何帮助将不胜感激：

完整代码：https://github.com/troy21688/xyz-reader-starter-code