Große Formel in Zelle schreiben

Sub SchreibeJahresFormel()
Dim jahr    As Variant
Dim diff    As Integer
Dim a       As Integer
a = 2
'Jahreszahl aus Feld auslesen
jahr = Workbooks(Konstanten.SelfName) _
.Worksheets(Konstanten.Hauptfenster) _
.[EingabeJahr].Value
'Differenz Anfangsjahr und aktuellem Jahr errechnen
diff = jahr - 1979 + 1
With Workbooks(Konstanten.SelfName) _
.Worksheets("TEST")
While a <= 42
.Range(.Cells(a, 3), .Cells(a, 3)).Formula = "=IF('Eingabe Mon'!$B$3='Eingabe monat'!$B$" & diff & ";FREQUENCY('Eingabe monat'!$C$" & diff & ":$AG$" & diff & ";monat!$A" & a & ":$A$42);'Jahreswechsel')"
a = a + 1
Wend
End With
End Sub