Printing Duplex both sides of paper

[danjw_98]

I am trying to print a daily calendar using the below vba macro and it won't print duplex on both sides of paper. any help would be appreciated. thanks..

For i = 0 To daysToPrint Step d
Range("theDate").Value = theStartDate + i
'MsgBox "Printing Page " & i + 1
ActiveWindow.SelectedSheets.PrintOut Copies:=1, Collate:=True
Next i