Alan,
The issue is most probably in the specific driver. The error that gets returned in TestStand is BFFA4005 which is a specific driver error (see NI IVI Driver Help). Since we do not have access to the source code of the Pickering driver, you should contact their support channels. Although you said that everything works fine in CVI 7.0 using virtual names, I think you could come across the same issue if you would just use a different order of calls such as Connect, followed by the GetPath, and then SetPath functions.
Best Regards,
Vesna Jadric
Instrument Drivers/IVI
National Instruments