Hi,
Are there any instruments attached to the bus? If so have you double checked the cables to make sure that they are secure? Is your instrument set to enable GPIB communication? Does the GPIB card past the tests? Assuming you are using MAX, have you tried pressing the F5 key to refresh the list?
If you provide some more detail, I can do my best to help you out.
Best Regards,
Aaron K.
Application Engineer
National Instruments
