The button is not displayed when testing the application, how to fix it?

Question

Android

The Activity has a button. When starting the emulator - no. The Buttons work, but the ones that don't are the ImageButtons, although they were also displayed a few moments ago. All I changed was to stretch them out a bit in the GUI.
Here is the activity text:

<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" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin" tools:context=".QuizActivity">


    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="24dp"
        android:id="@+id/question_text_view"
        android:layout_above="@+id/linearLayout"
        android:layout_centerHorizontal="true" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:id="@+id/linearLayout"
        android:layout_centerVertical="true"
        android:layout_centerHorizontal="true">


        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/false_button"
            android:id="@+id/falseButtonId"/>

        <Button
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="@string/true_button"
            android:id="@+id/trueButtonId" />
    </LinearLayout>

    <ImageButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/next_button"
        android:src="@drawable/arrow_right"
        android:layout_below="@+id/linearLayout"
        android:layout_alignEnd="@+id/linearLayout"
        android:layout_toEndOf="@+id/question_text_view"
        android:cropToPadding="false" />

    <ImageButton
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/prevButton"
        android:src="@drawable/arrow_left"
        android:layout_below="@+id/linearLayout"
        android:layout_alignStart="@+id/linearLayout"
        android:layout_toStartOf="@+id/question_text_view" />

</RelativeLayout>

Answer 1

What is the minimum supported sdk version? For ImageButton you are using attributes that are only available from version 17