Have you gotten the two signals? If not, you might consider posting to the GPIB forum.
Here are two links to others asking the same question. http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RNAME=ViewQuestion&HOID=506500000008000000E1950000&ECategory=Measurement+Hardware.Dynamic+Signal+Acquisition+and+Analysis http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RNAME=ViewQuestion&HOID=506500000008000000D62B0000&ECategory=LabVIEW.LabVIEW+General
