Compiler/MSP-EXP430FR2355: the ADC of msp430fr2355

Tool/software: TI C/C++ Compiler

I use MSP-EXP430FR2355 to debug ADC part. I think MSP430FR2355  has 12-bit ADC,but I get  the  ADvalue is wrong.
My Iinput DC level is 1.14V,I get the value is 350 ,if I calculate with 10-bit ADC:350/1024*3.3=1.14V,the data is right,

but  12-bit ADC,350/4096*3.3=0.28V.  Please help me !

#include "msp430fr2355.h"

unsigned int ADvalue;
void ADC12Init(void);

void main(void)

{

ADC12Init();
_EINT();
ADCCTL0|=ADCSC; 

while(1);
}

void ADC12Init(void) 
{
ADCCTL0 &=~ADCENC ; 
ADCCTL0 = ADCON; 

ADCCTL1 = ADCCONSEQ_0+ADCSHP+ADCSSEL_0; 

ADCMCTL0=ADCINCH_0+ADCSREF_0;
ADCIE =ADCIE0 ; 
ADCCTL0 |= ADCENC; 
}

#pragma vector=ADC_VECTOR
__interrupt void ADC(void)
{
switch(ADCIV)
{
case ADCIV_0:break;
case ADCIV_2:break;
case ADCIV_4:break;
case ADCIV_6:break;
case ADCIV_8:break;
case ADCIV_10:break;

case ADCIV_12:
ADvalue =ADCMEM0;

ADCCTL0 |=ADCSC; 
default:break;
}
}