ListViewItem Event Setter

I tried subclassing Listview and doing this...

 var style = new Style(typeof(ListViewItem));

            style.Setters.Add(new EventSetter(MouseEnterEvent, new RoutedEventHandler(MouseEnter_Handler)));

            Resources.Add(typeof(ListViewItem), style);

didnt work, nothing....

Changing the MouseEnterEvent to say leftmousedown then works.... weired. An ideas