Visual Basic.NET - Recorrer listview en WPF

Dim litem1 As ListViewItem = TryCast(obj, ListViewItem)

For L = 0 To ListView1.Items.Count - 1

                litem1 = ListView1.Items(L) ' AQUI LANZA EL ERROR

next

Private Sub LlenaListview()

                 StrSql = "select * from SubFamilia Where IdGrupo   ='" &    Me.Cbo_grupo.SelectedValue.trim & "'"

            StrSql += " And IdSubGrupo='" & Me.Cbo_Subgrupo.SelectedValue.trim & "'"

            StrSql += " And IdFamilia='" & Me.Cbo_Familia.SelectedValue.trim & "'"

            ListView1.DataContext = Conexion.EjecutaDataTable(StrSql)

End Sub

Me.PonerListview()

   Me.LlenaListview()

private   Sub PonerListview()

        ListView1.Items.Clear()

        Dim view = New GridView()

        view.Columns.Add(New GridViewColumn() With {.Header = "Código", .Width = 50, .DisplayMemberBinding = New Binding("codigo")})

        view.Columns.Add(New GridViewColumn() With {.Header = "Descripción", .Width = 450, .DisplayMemberBinding = New Binding("descrip")})

        ListView1.View = view

End Sub

Private Sub LlenaListview()

        StrSql = "select * from colores order by DescripcionColor"

        Dim DatareaderSQL As SqlDataReader = Conexion.EjecutaDataReaderSQL(StrSql)

        If DatareaderSQL.HasRows Then

            While DatareaderSQL.Read

                If Not IsDBNull(DatareaderSQL.Item("IDColor")) Then

                    Dim Codex As String = Trim(DatareaderSQL.Item("IDColor"))

                    Dim Descrip As String = Trim(DatareaderSQL.Item("DescripcionColor"))

                    ListView1.Items.Add(New With {.codigo = Codex.Trim, .descrip = Descrip.Trim})

                End If

            End While

        End If

End Sub

Private Sub Button_Click_1(sender As Object, e As RoutedEventArgs)

        Dim litem1 As String

        Dim litem2 As String

        Dim litem3 As String

        Dim litem4 As String

        For i = 0 To ListView1.Items.Count - 1

            litem1 = Me.ListView1.SelectedItems(0).codigo() 'item seleccionado

            litem2 = Me.ListView1.SelectedItems(0).descrip() 'item seleccionado

            litem3 = Me.ListView1.Items(i).codigo()  'item

            litem4 = Me.ListView1.Items(i).descrip()   'item

        Next

End Sub