cardview not showing cornerRadius and elevation

I created a card view in a recycler view and my codes work well but the problem now is that the cardview does not show the rounded edges and elevation at runtime but it shows in the design codes. my codes are shown blow

activity_main

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".Controller.MainActivity">

    <uk.co.markormesher.android_fab.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:buttonIcon="@drawable/ic_add_group"
        />

    <android.support.v7.widget.RecyclerView
        android:id="@+id/groupListView"
        android:layout_width="0dp"
        android:layout_height="0dp"
        android:layout_marginBottom="8dp"
        android:layout_marginTop="8dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</android.support.constraint.ConstraintLayout>

my card_view.xml

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="wrap_content">

<android.support.v7.widget.CardView
    android:id="@+id/groupCardView"
    android:layout_width="match_parent"
    android:layout_height="128dp"
    android:layout_marginEnd="16dp"
    android:layout_marginStart="16dp"
    android:layout_marginTop="24dp"
    app:cardCornerRadius="10dp"
    app:cardElevation="5dp"
    app:cardUseCompatPadding="true"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent">

    <android.support.constraint.ConstraintLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@android:color/transparent">

        <TextView
            android:id="@+id/groupTitle"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_marginBottom="8dp"
            android:layout_marginEnd="8dp"
            android:layout_marginStart="8dp"
            android:layout_marginTop="8dp"
            android:text="Trips"
            android:textAlignment="center"
            android:textSize="30sp"
            app:layout_constraintBottom_toBottomOf="parent"
            app:layout_constraintEnd_toEndOf="parent"
            app:layout_constraintStart_toStartOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
    </android.support.constraint.ConstraintLayout>
</android.support.v7.widget.CardView>

I do not know what I have done wrong