Adding pictures to textboxes

Question

On a document in Word there is a table in which I have put textboxes.

Now I want to add pictures to these textboxes.

I use the code written below. But, although pictures get written, they are placed outside the textboxes. How can I make sure that they are placed within the boxes?

Sub AfbeeldingenLaden()
    Dim tekstvak As Shape
    Dim Bestandsnamen() As String
    Dim i As Integer

    Bestandsnamen = AfbeeldingenKiezen()

    For Each tekstvak In ActiveDocument.Shapes
        If tekstvak.Height > 20 Then

 tekstvak.Select

            If Bestandsnamen(i) <> "" Then
                  Selection.InlineShapes.AddPicture Bestandsnamen(i), False, True
            End If
            i = i + 1
        End If
    Next
End Sub

I've also tried the following, but that gives a Type Mismatch error:

For Each tekstvak In ActiveDocument.Shapes
   If tekstvak.Height > 20 Then

        tekstvak.Select
        If Bestandsnamen(i) <> "" Then
            Dim rng As Word.Range Set rgn = tekstvak.TextFrame.TextRange.Paragraphs(1).Range
            ActiveDocument.InlineShapes.AddPicture FileName:=Bestandsnamen(i), LinkToFile:=False, SaveWithDocument:=True, Range:=rng
        End If
        i = i + 1
    End If
Next