Due analog input pull-up resistor not working

Hardware Arduino Due
6

I Also Also tried more possibilities

void setup() {
  // initialize serial communications at 9600 bps:
  SerialUSB.begin(57600);

  // digitalWrite(A0, HIGH);
  // REG_PIOA_SODR = 0x3FFF;
  //adc_enable_all_channel(ADC);
  ADC->ADC_MR |= 0x80;  //set free running mode on ADC
  ADC->ADC_CR = 2;
  ADC->ADC_CHER = 0x3FFF;
  PIOA->PIO_PUER |= PIO_PA16;
  PIOA->PIO_SODR |= PIO_PA16;
  PIO_PullUp(PIOA, PIO_PA16, PIO_PULLUP);

}


void loop() {
  int t = micros();
  int a[11];

  while ((ADC->ADC_ISR & 0x3FFF) != 0x3FFF);
  a[0] = ADC->ADC_CDR[7];
  a[1] = ADC->ADC_CDR[6];  
  a[2] = ADC->ADC_CDR[5];
  a[3] = ADC->ADC_CDR[4];
  a[4] = ADC->ADC_CDR[3];
  a[5] = ADC->ADC_CDR[2];
  a[6] = ADC->ADC_CDR[1];
  a[7] = ADC->ADC_CDR[0];
  a[8] = ADC->ADC_CDR[10];
  a[9] = ADC->ADC_CDR[11];
  a[10] = ADC->ADC_CDR[12];
  a[11] = ADC->ADC_CDR[13];


  t = micros() - t;
  SerialUSB.print("1  conversion in All Channels  "); SerialUSB.print(t); SerialUSB.println(" micros");
  SerialUSB.print("A0 total:"); SerialUSB.println(a[0]);
  SerialUSB.print("A1 total:"); SerialUSB.println(a[1]);
  SerialUSB.print("A2 total:"); SerialUSB.println(a[2]);
  SerialUSB.print("A3 total:"); SerialUSB.println(a[3]);
  SerialUSB.print("A4 total:"); SerialUSB.println(a[4]);
  SerialUSB.print("A5 total:"); SerialUSB.println(a[5]);
  SerialUSB.print("A6 total:"); SerialUSB.println(a[6]);
  SerialUSB.print("A7 total:"); SerialUSB.println(a[7]);
  SerialUSB.print("A8 total:"); SerialUSB.println(a[8]);
  SerialUSB.print("A9 total:"); SerialUSB.println(a[9]);
  SerialUSB.print("A10 total:"); SerialUSB.println(a[10]);
  SerialUSB.print("A11 total:"); SerialUSB.println(a[11]);

  delay(2000);
}

And also nothing work.