Greetings,
You will need to install the following drivers to use your NI-435X:
NI-DAQ 6.9.1 (or later)
IVI Engine 1.61 (or later)
VISA 2.5.2 (or later)
After installing these three drivers, you should then install the NI-435X driver.
If you are missing any of these drivers, they can be downloaded from the following location:
http://digital.ni.com/softlib.nsf/MainPage?ReadForm&node=132010_US
Good luck with your application.
Spencer S.