I am trying to retrieve device-friendly name from class-guid. I am getting an error back indicating INVALID_CLASS_NAME  on using SetupDiGetClassDescriptionEx. How-ever, on calling SetupDiGetClassDevsEx with same class-guid to get HDEVINFO it is working fine. Hence I am not sure why I getting the error on only using SetupDiGetClassDescriptionEx. Someone please help.
P.S: Any other mechanism of retrieving device friendly name is also fine for me.. Just want a method to get it.