Dim TMP As String
Private Sub Worksheet_Change(ByVal Target As Range)
If Target.Address = "$A$1" Then
If UCase([b1]) = "OK" And Target.Value <> TMP Then [a1] = TMP
End If
End Sub
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
If Target.Address = "$A$1" Then TMP = Target.Value
End Sub