Error Setting Cell Locked Property

[Ark68]

Here is a chunk of my code ...

        For et = 0 To 9
            If ar_cntevent(et) <> 0 Then
                .Cells(rw, "AS") = ar_cntevent(et)
                .Cells(rw, "AR") = ar_eventtype(et)
                With .Range("AP" & rw & ":AR" & rw)
                    .Merge
                    .HorizontalAlignment = xlRight
                    .VerticalAlignment = xlCenter
                    .locked = false
                End With
                rw = rw + 1
            End If
        Next et

The line highlighted in red is giving me an "Unable to set the Locked property of the Range class".
I'm am unsure why I am getting this error nor how to resolve it.