DownloadStringAsync DownloadStringCompleted issue

I want to download a file in Silverlight. It works in normal VB just fine:

VB-Download Code:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
        Dim wclient As Net.WebClient = New Net.WebClient()
        AddHandler wclient.DownloadStringCompleted, AddressOf ListDownloaded
        wclient.DownloadStringAsync(New Uri("blablabla.txt"))
    End Sub
    Private Sub ListDownloaded(ByVal sender As Object, ByVal e As Net.DownloadStringCompletedEventArgs)
        MessageBox.Show(e.Result)
    End Sub

But in Silverlight VB...

Silverlight-Download Code:

Private Sub ListDownloaded(ByVal sender As Object, ByVal e As Net.DownloadStringCompletedEventArgs)
        MessageBox.Show(e.Result)
    End Sub
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles Button1.Click
        Dim wclient As Net.WebClient = New Net.WebClient()
        AddHandler wclient.DownloadStringCompleted, AddressOf ListDownloaded
        wclient.DownloadStringAsync(New Uri("blablabla.txt"))
    End Sub

It utterly fails. At the bottom of Firefox it SAYS the file is downloading, but NOTHING happens other than that...

HELP!