Help Me Debug my 2 bit M DAC for my 6 bit Pipeline ADC with 2 bit - 3 stage configuration.

I am trying to make Pipeline ADC for my Mixed - Signal Project, i try to simulate it first in LTSPICE before I layout and simulating in in Cadence Virtuoso, but my M DAC using Summer Switch Capacitor Amplifier failed... The Characteristic function for the last quantization not working, i confused. Here is the LTSPICE file.



For the 2 bit Flash ADC i use TIQ - Flash ADC (it already worked)