I have my AT-MIO-16D-9L board configured in RSE mode and am reading the output from three channels in my acquisition program. When I have a source (such as battery) connected to two of the channels, those two channels give an accurate reading. The third "open" channel does not read exactly 10 V (internal reference) though. Can anyone propose a solution (or even possible cause) to this? The problem seems to get worse when the sampling time is increased. Thanks in advance.