Debugging 005 ADC encountered some problems, ask for help

AIN0 (P24), AIN2 (P32), AIN3 (P33) are used as the three ADC ports. When AIN0 is selected, there is a 3.1V voltage on the P24 pin, and the ADC conversion result is 3.1V. It is no problem to select the other two channels . There is no voltage on the P24 pin when the other two channels are selected.
Is there something wrong with my settings?