change styles.xml in Android

hi, I have tried to add a styles.xml to the xamarin.forms.android project in resources/values to change the selected color of a listview but it doesn't works, any idea about this?

<?xml version="1.0" encoding="UTF-8" ?>
<resources>
  <style name="MyTheme" parent="android:style/Theme.Holo.Light">
   <item name="android:colorPressedHighlight">@color/ListViewSelected</item>
   <item name="android:colorLongPressedHighlight">@color/ListViewHighlighted</item>
   <item name="android:colorFocusedHighlight">@color/ListViewSelected</item>
   <item name="android:colorActivatedHighlight">@color/ListViewSelected</item>
   <item name="android:activatedBackgroundIndicator">@color/ListViewSelected</item>
  </style>
<color name="ListViewSelected">#96BCE3</color>
<color name="ListViewHighlighted">#E39696</color>
</resources>