Hi jdk,
I think it could be just an installation issue. I assume that you are using Mac 9.1. I've run LV 6.1 with NIDAQ 6.6.1 on Mac 9.1 and it works just fine, including DAQ-STC counter functions.
If LabVIEW 6.1 was installed without DAQ support, run the LabVIEW 6.1 installer and perform a custom installation for DAQ support. Then, run
the NI-DAQ 6.6.1 installer to upgrade NI-DAQ.
Hope this helps.
Regards,
Pravin Borade
Applications Engineer, National Instruments