Thank you Logan for this feedback.
We upgraded to NI-DAQmx 8.0 a couple of month ago, and I went to this calibration palette where I was glad to see SCXI functions, indeed.
As our project had to be finished much earlier, we had to find a workaround for that by performing a custom scaling operation instead of a conventional calibration... 
But be sure next time we would need to use SCXI, I will make a try to these functions 