what should I do
Stop ignoring our questions and explanations about exsisting hardware problems.
It has been pointed out that the connections to the LTC1021 are incorrect. You were asked in post #7 to measure voltages that would confirm this.
You continue to ignore these facts and questions.
To be absolutely clear: the output of the LTC1021 is connected to one point only, the REF input of the ADC. The LTC2414 VCC pin should be connected to the 5 volt output of the Uno.