Your best VISA troubleshooting utility is the VISA Interactive Control (nivisaic.exe). From this utility, you can use the VISA protocol to communicate with each of the VISA resources available on you system. If you are unable to get this utility to properly recognize or use your NI-GPIB card, It may be suggested to uninstall/reinstall the NI-VISA distribution. If you can get the utility to work then there is a programmatic problem which you must address. Debugging programmatic issues is best troubleshot using the VISAIC utility, NI-SPY (nispy.exe), and highlight execution. If you can outline a flow from within VISAIC, using NI-SPY you can log this flow and attempt to emulate it from within LabVIEW. Make sure each of the functions has the proper inputs. Also, try usin
g some of the VISA/GPIB examples shipped with LabVIEW.
Ryan Mosley