Building on the answer to your post here, the only USB devices supported in NI-DAQ 6.8 are the old DAQPad E Series USB devices such as the NI DAQPad-6015 or DAQPad-6016. All M Series devices, including the USB variants, are only supported in NI-DAQmx.
Seth B.
Principal Test Engineer | National Instruments
Certified LabVIEW Architect
Certified TestStand Architect