Hello;
The first thing to double check is if the input mode is set accordainly with the connections made.
The best bet is to revisit the AMUX Users Manual and double check the connections you made with the ones shown in the manual. Furthermore, go to MAX and check the input mode of the DAQ device.
Everything must match.
In case you got everything accordainly with the manual, and you still see the same behavior, the problem is probably hardware related.
Hope this helps.
Filipe A.
Applications Engineer
National Instruments