We are using an ad8222 configured as a differential amplifier as in figure 49 of the data sheet. We have +IN2 tied to AGND and REF2 tied to +Vs, with +Vs is set to 5.0v and -Vs is set to 0v. This should provide a common mode output voltage of 2.5v. The circuit appears to be fully functional at various gain settings and signal inputs. However, common mode voltage is physically measured at 3.45v. Any ideas why there is a discrepency?