Android Calendarview, months overlapped

Question

I'm trying to use the Calendarview widget in my activity, but I have a big problem. The only thing I wrote down is my activity:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <CalendarView
        android:id="@+id/calendar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        />
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@id/calendar"
        android:textColor="@color/black"
        android:layout_alignParentStart="true"
        android:id="@+id/label_tot"
        android:text="@string/tot" />
    <TextView
        android:layout_toEndOf="@id/label_tot"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/calendar"
        android:layout_marginLeft="10dp"
        android:id="@+id/tot"
        android:textColor="@color/black"
        android:text="prova"/>

</RelativeLayout>

And then, when I change the date I got

You can see two months overlapped.