OpenBySerial Failing under Linux

I am trying to configure an FPGA under RedHat Enterprise 5 using the C++ API. I am able to successfully load the .so library, but then OpenBySerial() fails. I have the Opal Kelly board connected and it shows up under /dev/bus/usb/devices. Should I be passing a string or device ID to OpenBySerial(), or is there something else I need to do to run under Linux?

Thanks very much,

What ErrorCode do you get?