Title says 1-ksps on p.10, and for this specific sampling rate error is very big:
C, pF F, Hz R, Ohm R-lpf Error, %
15 1000 10610329.5 200000 1.85008236122648
where C - capacitance S/H, and error is calculated as two resistors voltage divider. To get 1/2 LSB sampling rate has to be less than 5 sps.