How to bring progress bar in top of layout

I have included a progress bar in my relative layout, but it is running behind the layout. Is there any way I can bring it in front show that it show when the page is loading.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:layout_gravity="center"
    android:background="@color/pageBackgroundColor"
    android:gravity="center"
    tools:context="co.sd.app.CheckoutActivity">

    <ProgressBar
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:visibility="visible" />

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_above="@+id/relativeLayout"
        android:layout_marginLeft="@dimen/page_marging_left"
        android:layout_marginRight="@dimen/page_marging_right">

        <android.support.v7.widget.AppCompatTextView
            android:id="@+id/service_detail_cv"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignParentLeft="true"
            android:layout_below="@+id/shedule_apt_cv"
            android:layout_marginBottom="@dimen/dim_10sp"
            android:layout_marginTop="@dimen/dim_10sp"
            android:textColor="@color/darkGrey" />

    </RelativeLayout>

</RelativeLayout>

I have no idea why is it show like this.