Can someone suggest an alternative to what I'm doing here. I get an error on the "copy/paste values" here...

Masterbook.ActiveSheet.Range("A:D") = Tempbook.ActiveSheet.Range("A:D").Values
Full Code

Sub UpdateFS()
Application.ScreenUpdating = False
Dim Masterbook As Workbook
Dim Tempbook As Workbook
Dim Filename As String
Dim Pathname As String
Dim i As Integer
Application.DisplayAlerts = False
Set Masterbook = ActiveWorkbook
    For i = 1 To 2
        Filename = Range("M" & i).Text
        Pathname = "C:\Nathan\---COMPLETED REPORTS---\For Kristi\MONTHLY REPORTING\Wellington - Financial Statements\Consolidation\"
        Workbooks.Open Filename:=Pathname & Filename
        Set Tempbook = ActiveWorkbook
        If i = 1 Then
            Masterbook.ActiveSheet.Range("A:D") = Tempbook.ActiveSheet.Range("A:D").Values
            Tempbook.Close
        Else
            Masterbook.ActiveSheet.Range("F:I") = Tempbook.ActiveSheet.Range("A:D").Values
            Tempbook.Close
        End If
    Next i
    Application.DisplayAlerts = True
End Sub