WPF VB.NET : how to insert a notepad in listbox

I already used the code as below.

 Dim openfile1 = New Microsoft.Win32.OpenFileDialog With {.Filter = "Text (*.Text)|*.txt"}
        If (openfile1.ShowDialog() = System.Windows.Forms.DialogResult.OK) Then
            For Each line As String In File.ReadAllLines(openfile1.FileName)
                ListBox1.Items.Add(line)
            Next
        End If

This code serves on windows form, when I use in WPF there are no errors but can not display the contents of the notepad on the listbox. there is no other solution