I can't retrieve the ListBox selecteditem

Hi everybody,

I'm not able to cath any ListBox selected item.

XAML definition:

<Popup x:Name="contextMenu" Opened="contextMenu_Opened" Closed="contextMenu_Closed"><Grid x:Name="GridMenu" Opacity="2"><Border><ListBox x:Name="contextListBox" 
PreviewMouseLeftButtonUp="contextListBox_PreviewMouseLeftButtonUp" 
Foreground="White" Background="White" /></Border></Grid></Popup>

Code-behind.

List class definition for the items:

Public Class Links

    Public _title As String
    Public _url As String
    Public Property url() As String
        Get
            Return _url
        End Get
        Set(ByVal value As String)
            _url = value
        End Set
    End Property
    Public Property title() As String
        Get
            Return _title
        End Get
        Set(ByVal value As String)
            _title = value
       End Set
    End Property
    Public Sub New(t As String)
        title = t
    End Sub
End Class

Populating my list:

Public _links As New List(Of Links)

        _links.Add(New Links("Sustitución"))
        _links.Add(New Links("Daños fuertes"))
        _links.Add(New Links("Daños medios"))
        _links.Add(New Links("Daños leves"))
        _links.Add(New Links("Pintado superficial"))

Populating my ListBox:

contextListBox.Items.Clear()

For Each l As Links In _links

Dim hlb As New Hyperlink

hlb.Inlines.Clear()
hlb.Inlines.Add(l.title)

contextListBox.Items.Add(hlb)

Next

Here, my "s" variable has nothing as value..

PrivateSub contextListBox_PreviewMouseLeftButtonUp(senderAsObject, eAsMouseButtonEventArgs)

       DimsAsString=Me.contextListBox.SelectedValue

EndSub

Nevertheless, contextListBox.Items.Count is equal to 5 in that point, that means is loaded...

What am I missing here?

ListBox is under one ContextMenu object.

Thanks a lot for your thoughts,

Primary platform is Windows 7 Ultimate 64 bit along with VS 2012/Sql2k8 for WPF/SilverLight projects.