Error -1073807346

when I tried to run the Agilent 415X Series Dual Source Sweep Display.vi, always to get the message below,

Error -1073807346 occurred at VISA Open in Agilent 415X Series.lvlib:Initialize.vi->Agilent 415X Series Dual Source Sweep Display.vi

I don't understand what does this mean and how to fix it.

Thanks!