Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
   
    Sheets(2).Select
    Dim i As Long
    Dim sTxt As String
    For i = 1 To 100
        If Len(Cells(i, 1)) > 0 Then
            If Len(Cells(i, 3)) = 0 Then
                sTxt = sTxt & Cells(i, 3).Address(rowabsolute:=False, columnabsolute:=False) & ", "
            End If
        End If
    Next i
    If Len(sTxt) > 0 Then
        MsgBox "Du mangler at udfylde cellerne: " & sTxt
        Cancel = True
    End If
   
End Sub