wpf databinding in usercontrol doesn't work

Hello,

When I run following code in a window the binding works normally. But when I do the same thing but make it a usercontrol it stops working.

I've tried so many things but I'm very very new to WPF and in need of help.

Please help ;-) !

window.xaml

<Window x:Class="testwpfgrid.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525"
        DataContext="{Binding RelativeSource={RelativeSource Self}}"><StackPanel><ListView Name="lv" ItemsSource="{Binding Path=AvosEntries}" IsSynchronizedWithCurrentItem="True"><ListView.View><GridView AllowsColumnReorder="true" ColumnHeaderToolTip="Avos Information"><GridViewColumn DisplayMemberBinding="{Binding Path=AvosName}" Header="Avos Name" Width="100"/></GridView></ListView.View></ListView><Button HorizontalAlignment="Right" Margin="5,5,5,5" Content="Add Row" Click="AddRow_Click" /></StackPanel></Window>

window.xaml.cs

public partial class MainWindow : Window
    {
        public class AvosEntry
        {
            public string AvosName { get; set; }
        }
        public MainWindow()
        {
            AvosEntries = new ObservableCollection<AvosEntry>();
            fillList();
            InitializeComponent();
        }
        private void AddRow_Click(object sender, RoutedEventArgs e)
        {
            AvosEntries.Add(new AvosEntry
            {
                AvosName = "New Avos Entry"
            });
        }
        private void fillList()
        {
            for (int i = 1; i <= 10; i++)
            {
                AvosEntry avosEntry = new AvosEntry();
                avosEntry.AvosName = "Avos " + i;
                AvosEntries.Add(avosEntry);
            }
        }
        public ObservableCollection<AvosEntry> AvosEntries { get; private set; }	
    }

if i do the same thing but make some changes to it so it is a UserControl instead of a Window (and load the usercontrol into another application and display it, I get a different result... (the object.toSting() is displayed as the value in the cells))

Kind Regards!