button is invisible

[sandeepgahlawat]

 <style name="LightFlatColorButtonRippleStyle" parent="Material.Drawable.Ripple.Touch.Light">
        <item name="android:background">@null</item>
        <item name="rd_backgroundColor">@color/primary</item>
        <item name="rd_rippleColor">@color/accent</item>
        <item name="rd_cornerRadius">4dp</item>
        <item name="rd_delayClick">afterRelease</item>
        <item name="rd_maskType">rectangle</item>
        <item name="android:textAppearance">@style/Base.TextAppearance.AppCompat.Button</item>
        <item name="android:textColor">@color/white</item>
    </style>




 <com.rey.material.widget.Button
        style="@style/LightFlatColorButtonRippleStyle"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_gravity="bottom"
        android:layout_marginBottom="10dp"
        android:layout_marginEnd="10dp"
        android:layout_marginLeft="10dp"
        android:layout_marginRight="10dp"
        android:layout_marginStart="10dp"
        android:text="BUTTON"
        android:textAllCaps="true"
        android:textSize="18sp"
        app:rd_enable="true" />

This is how I am using your library to add Button to my project but the problem is that the button appears invisible and only shows color upon touching the button . If I remove the
<item name="android:background">@null</item> tag from the style button becomes grey and if I set the background to some color then there are no corner radii.

Please help