ListView not displaying observablecollection

Question

XAML:

<Window x:Class="MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    DataContext="{Binding RelativeSource={RelativeSource Self}}"
    Title="Rocking Robin" Height="350" Width="525">
    <Grid>
        <DockPanel>
            ...
                    <ListView Name="lvLibrary" ItemsSource="{Binding _SongLibrary}">
                        <ListView.View>
                            <GridView>
                                <GridViewColumn Width="120" Header="Title" DisplayMemberBinding="{Binding Title}"></GridViewColumn>
                                <GridViewColumn Width="120" Header="Artist" DisplayMemberBinding="{Binding Artist}"></GridViewColumn>
                                <GridViewColumn Width="120" Header="Album" DisplayMemberBinding="{Binding Album}"></GridViewColumn>
                                <GridViewColumn Width="0" Header="FileName" DisplayMemberBinding="{Binding FileName}"></GridViewColumn>
                            </GridView>
                        </ListView.View>
                    </ListView>
                ...
</Window>

And code:

Class MainWindow
    Public _SongLibrary As ObservableCollection(Of ASong)
   
   
   

    Private Sub btnLoad_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles btnLoad.Click
        Dim ofd As New Microsoft.Win32.OpenFileDialog

        ofd.Filter = "MP3 Files (*.mp3)|*.mp3"
        If ofd.ShowDialog = True Then
            Dim Sng As New ASong
            Sng.FileName = ofd.FileName
            Sng.Title = InputBox("Enter Title", "Title", "Default Title")
            Sng.Artist = InputBox("Enter Artist", "Artist", "Default Artist")
            Sng.Album = InputBox("Enter Album", "Album", "Unknown")
            _SongLibrary.Add(Sng)
        End If
    End Sub

    Public Sub New()

   
        ' Add any initialization after the InitializeComponent() call.
        _SongLibrary = New ObservableCollection(Of ASong)

    End Sub
End Class

The play event fires, but there's nothing displayed.