How to check a CheckBox inside a WPF Listview using VB.net

Hi I have been unable to solve this issue. I have this list view

But I'm unable check the checkbox programatically

Private Sub checkBox1_Click(sender As Object, e As RoutedEventArgs) Handles checkBox1.Click For Each LITEM In ListView1.Items LITEM.IDEM = False Next End Sub

Public Class ListViewItemTemplate Public Property IDEM As String End Class

How can I do this?