Laufzeitfehler 13 - Typen unverträglich

Private Sub Worksheet_Calculate()
Zeitstart = "15:29:00"
zeitende = "22:00:00"
zeitende1 = "21:00:00"
Dim i As Integer
For i = 40 To 634
Datf = Format(Time, "hh:mm:ss")
If Datf < Zeitstart Then End
If Datf > zeitende Then End
'   Verkaufszeit
If Cells(i, 198) = "x" Or Cells(i, 198) = "y" Or Cells(i, 198) = "z" And IsEmpty(Cells(i, 197)) Then
Cells(i, 197) = Format(Now, "hh:mm:ss")
Cells(i, 202) = Cells(i, 21)
End If
'   Kaufzeit
If Datf > zeitende1 Then GoTo ZW1
If Cells(i, 15) = "F" And IsEmpty(Cells(i, 196)) Then
Cells(i, 196) = Format(Now, "hh:mm:ss")
End If
ZW1:
Next
End Sub