What is the full name voice ?
The RealSpeak voices can be used only with Nuance products. This command looks like something used by the Microsoft corporation. In fact, it's described on the MSDN help pages. Access the pages to see exactly how it's used. Secondly, the voice should be available exact as it should. To get Windows Package name, use the guide on the following page: https://technet.microsoft.com/en-us/library/hh852175.aspx