Hello,
Have you tried changing the input mode? I'm not very sure what input mode you are using but I would recommend to use differential.
For troubleshooting bad readings, it is always advisable to read the signals from MAX (Measurement and Automation Explorer) first, and then use other programs like LabView, LabWindows/CVI or Measurement Studio.
If you want to use differential mode, here's how you would connect the signals: Connect DAC0 OUT to ACH0, and AOGND to ACH8.
Finally, here's a link to an interesting Knowledge Base:
Data Acquisition: Troubleshooting Offset, Incorrect, and Noisy ReadingsGood luc
k with your application!