Option Explicit
Private Sub CommandButton1_Click()
Dim Abschnitt, S, Zeile, Zeile2, Spalte2, Zelle1, Zelle2 As Integer
Abschnitt = 0
S = 1
Do
Zeile = S + Abschnitt
Zeile2 = S + 1 + Abschnitt
If Application.WorksheetFunction.CountA(Cells(Zeile, 16)) = 0 Or Application.WorksheetFunction.CountA(Cells(Zeile2, 16)) = 0 Then
Cells(Zeile, 17) = ""
Else
Cells(Zeile, 17) = Cells(Zeile, 16) + Cells(Zeile2, 16)
End If
Abschnitt = Abschnitt + 12
S = S + 1
Loop Until S > 3
End Sub