Summenformel in leere Zeile eintragen

Sub Leerzeile()
Dim wks1 As Worksheet
Dim i As Long
Dim lastrow As Long
Set wks1 = ActiveWorkbook.ActiveSheet
With wks1
Application.EnableEvents = False
lastrow = IIf(IsEmpty(Cells(Rows.Count, 3)), Cells(Rows.Count, 3).End(xlUp).Row, Rows.Count) '   _
_
_
UsedRange.SpecialCells(xlCellTypeLastCell).Row
For i = lastrow To 6 Step -1
If Cells(i, 3).Value = "" Or Cells(i - 1, 3).Value = "" Then
ElseIf Cells(i, 3).Value  Cells(i - 1, 3).Value Then
Rows(i).Insert
End If
Next i
Application.EnableEvents = True
End With
End Sub