adc中断进去之后无法出来

//#include "keypad.h"
#include "1602(zhp)LT.h"
//#include"舵机.h"
#include"BoardConfig.h"
/********************************************
软件延时
********************************************/
//typedef unsigned int uint;
//typedef unsigned char uchar;
#define CPU_F ((double)8000000)
#define DELAY_US(x) __delay_cycles((long)(CPU_F*(double)x/1000000.0))
#define DELAY_MS(x) __delay_cycles((long)(CPU_F*(double)x/1000.0))
#define delay_us(x) __delay_cycles((long)(CPU_F*(double)x/1000000.0))
#define delay_ms(x) __delay_cycles((long)(CPU_F*(double)x/1000.0))
#define num 20
unsigned char wan,qian,bai,shi,ge;
unsigned int results[num]={0};
unsigned char t=0;
unsigned int ave=0;
unsigned int filter[2];
void transform(unsigned int dat)
{
   wan=dat/10000+0x30;
   qian=dat%10000/1000+0x30;
   bai=dat%1000/100+0x30;
   shi=dat%100/10+0x30;
   ge=dat%10+0x30;
}
void main()
{
   WDTCTL = WDTPW+WDTHOLD;  //关闭看门狗
  BCSCTL1 &= ~XT2OFF;
   while(IFG1&OFIFG)
   {
     IFG1&= ~OFIFG;
     DELAY_US(50);
   }
   BCSCTL2 |= SELM_2+SELS+DIVS_3; //MCLK 8M,SMCLK 1M
   lcd_init1602 ();
   //keypad_init();
   //write1char1602(0,0,i/10+0x30);
   //BoardConfig(0xb8);//11111000
   //_EINT();

   WDTCTL=WDTPW+WDTHOLD;
   P6SEL|=BIT1;
   ADC12CTL0=ADC12ON+SHT0_8+SHT1_8+MSC;
   ADC12CTL1=SHP+CONSEQ_2+CSTARTADD_1;
   ADC12MCTL1=INCH_1;
   ADC12IE=BIT1;
   ADC12CTL0|=ENC;
   _EINT();
   ADC12CTL0|=ADC12SC;
   while(2);
}
#pragma vector=ADC_VECTOR
__interrupt void ADC12ISR()
{
   ADC12IFG=0X00;
   t++;
   filter[0]=ADC12MEM0;
   if(filter[0]-filter[1]>5)
     ave=ave+filter[1];
   else
     ave=ave+filter[0];
   if(t==11)
   {
     t=0;
     ave=(unsigned int)(ave/11);
     transform(ave);
     write1char1602(0,0,wan);
     write1char1602(1,0,qian);
     write1char1602(2,0,bai);
     write1char1602(3,0,shi);
     write1char1602(4,0,ge);
     ave=0;
   }
   filter[1]=filter[0];

}
我明明读了ADC12MEM啊，为什么还是不能清除ADC12IFG呢？