Support for the USB-6221 was added in NI-DAQmx 8.6.1, which only supports back to LabVIEW 7.1. Unfortunately, there is not a version of the NI-DAQmx driver that supports both the USB-6221 and LabVIEW 6.0.2.
Seth B.
Principal Test Engineer | National Instruments
Certified LabVIEW Architect
Certified TestStand Architect