Ghost point in analog input to myRIO

[sharon_merry]

Ghost points spotted randomly when taking analog input value using myRIO. Voltage value from a device is to be displayed using labVIEW in a chart form. the voltage output from the display is connected to C/AI0 (output from 1 to 0+ and output from 2 to 0-). The voltage display in the chart will shoot up to the maximum value of 10V at certain point. However, the value obtained when measure the voltage of the device directly using voltmeter is around -0.002V to -0.003V at all times. 

May I know how to remove the "ghost" point?