Isso é o que acabei usando. Funciona perfeitamente.
' Following Inputs Exchange Date (L1) and Time (N1) into next available cell in column A
With ActiveSheet
With .Cells(Rows.Count, "A").End(xlUp).Offset(1, 0)
.Value = Application.Evaluate("CONCATENATE(L1,N1)")
.WrapText = False
End With
End With