Microsoft 365 VBA débutante problème boucle

Sub concatenerdoublons()
Dim i As Long
Dim chaine As Variant
Range("E:F").ClearContents
For i = 1 To Range("A1").End(xlDown).Row
    If WorksheetFunction.CountIf(Range("E:F"), "=" & Cells(i, 1).Value) = 1 Then
    chaine = Range("E:E").Find(What:=Cells(i, 1).Value, After:=Range("E1"), LookIn:=xlFormulas, LookAt _
        :=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlNext, MatchCase:= _
        False, SearchFormat:=False).Offset(0, 1) & " / " & Cells(i, 2)
    Range("E:E").Find(What:=Cells(i, 1).Value, After:=Range("E1"), LookIn:=xlFormulas, LookAt _
        :=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlNext, MatchCase:= _
        False, SearchFormat:=False).Offset(0, 1) = chaine
    Else
    If IsEmpty(Range("E1")) Then
        Range("e65536").End(xlUp) = Cells(i, 1)
        Range("f65536").End(xlUp) = Cells(i, 2)
    Else
        Range("e65536").End(xlUp).Offset(1, 0).Value = Cells(i, 1)
        Range("f65536").End(xlUp).Offset(1, 0).Value = Cells(i, 2)
    End If
    End If
Next i
End Sub