I'm not positive but from reading the context help on the 'range' input it appears as though the negative value that they are referring to is -1. I'm also lead to believe this because it says that the default is set to auto range on and in LabVIEW the default parameters are shown in the text labels for the inputs (-1.00E+0 for range). I don't have the instrument so I can't verify that, but that is my interpretation of the documentation. Hope that is helpful.
JR A.
Application Engineer
National Instruments
http://www.ni.com/ask