TextView未显示在RelativeLayout中的ImageView下

<RelativeLayout
    ...>

    <ImageView
        android:id="@+id/imageView"
        ... />

    <TextView
        android:id="@+id/textView"
        android:layout_below="@id/imageView"
        ... />

</RelativeLayout>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:src="@drawable/image"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp"
        tools:ignore="ContentDescription" />

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        android:layout_below="@id/imageView"
        android:layout_centerHorizontal="true"
        android:layout_marginTop="20dp" />

</RelativeLayout>