acquisition analog voltage Ni USB 6259: inverted signal

Hello,

I have aUSBNi6259BNC
I createdan analogvoltageacquisitiontaskwithNiDAQMXon waysfrom AL0 toAL8
I dealwithDasyLab(acquisitionI /O->displayChartRecorder)

MyPBis that theBNCsignal (coming hereaGBF) shall be reversedon the plugofUSB-6259, else, all channelsdisplay the samesignal(seescreencapture)

-BNCmass on theoutside,soulon theBNCcenter->all channelsposters the same signal.

-BNCmass becomesthe center andthe soulbecomescoaxaileoutside->Al0thewaythat displays thesignal, the others way stay at 0  level

 

on the housingUSB6259cursorstechnique areallonFS,

NIDAQmxtask ismassdifferentialmode (see attachedNIspot).

 

Where ismy mistake?

thank youfor yourexpertise