Problem with copy to next empty row

Hi,
I'm getting an error with these three lines, from the code below. Why?

                    R1.Offset(-i, 0).EntireRow.Copy _
                    Destination:= _
                    CD.Range("A1").End(xlDown).Offset(1, 0)

Help please.

Option Explicit

Public Sub DataForRStatistics()

Dim NR As Worksheet: Set NR = Worksheets("NorthernRoutesSunday8")
Dim CD As Worksheet: Set CD = Worksheets("CleanData")

Dim R1, R2 As Range

Dim i As Integer

With NR
    For Each R1 In .Range("C2:C" & .UsedRange.Rows.Count)
        If R1.Value = 6 Then
                For i = 1 To 6
                    R1.Offset(-i, 0).EntireRow.Copy _
                    Destination:= _
                    CD.Range("A1").End(xlDown).Offset(1, 0)
                Next i
        End If
    Next R1
End With

End Sub