Hi,
Those subVIs that are missing are the instrument drivers for Agilent 54624A. I tried downloading the GPIB instrument drivers and it didn't work. It seems like the program you downloaded from Agilent is referring to ag5462xx Initialize.vi and so forth. Whereas, the IVI instrument drivers are named ag5462x Initialize.vi and so forth. You will have to check with Agilent (where you got the example from), and see if they have any RS-232 based instrument drivers. If not, you can try using the regular GPIB based IVI drivers. You'll have to change your code a little bit to accomodate this.
A.S.
Anu Saha
Academic Product Marketing Engineer
National Instruments