android – CollapsingToolbarLayout ImageView不可滚动

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

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/collapsing_toolbar"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        android:fitsSystemWindows="true"
        app:contentScrim="?attr/colorPriMary"
        app:expandedtitleMarginStart="48dp"
        app:expandedtitleMarginEnd="64dp">

        <ImageView
            android:id="@+id/BACkdrop"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scaleType="centerCrop"
            android:fitsSystemWindows="true"
            app:layout_scrollFlags="scroll" 
            app:layout_collapseMode="parallax" />
            ...
    </android.support.design.widget.CollapsingToolbarLayout>

<android.support.v4.widget.nestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true"
    app:layouT_Behavior="@String/appbar_scrolling_view_behavior">
    ....

请注意,我已经添加了添加android：fillViewport =“true”到nestedScrollView并添加了app：layout_scrollFlags =“scroll”to
ImageView但是当试图从ImageView滚动时没有任何反应.