CCS/MSP430F2274: MSP430F2274 can't enter timer A ISR

#include <msp430.h>				
#include "msp430f2274.h"

unsigned int capArray[16] = {0};
unsigned char index = 2, flag = 0;
float hz = 0;

/*
 * 绝对值
 */
int abs(int x)
{
    return x>0?x:-x;
}


void HZ_Init()
{
    P2SEL |= BIT2;
    P2REN |= BIT6;
    P2DIR &= ~BIT2;
    P2DIR |= BIT6;

    CCTL0 = CM_1 + SCS + CCIS_0 + CAP + CCIE;
    TACTL = TASSEL_2 + MC_2;
}

/******************中断服务程序*****************************/
#pragma vector=TIMER0_A0_VECTOR
__interrupt void TIME0_A0_ISR(void)
{
    capArray[index--] = TA0CCR0;
    if(index == 0)
    {
        index = 2;
        TA0CCR0 = 0;
        flag = 1;
    }
}

/**
 * blink.c
 */
void main()
{
    double temp = 213.456;
    WDTCTL = WDTPW + WDTHOLD;
    HZ_Init();
    P2OUT &= ~BIT6;

    _EINT();
    while(1)
    {
        if (flag == 1)
        {
            temp = abs(capArray[1] - capArray[2]);
            hz = ((double )(1000000))/temp;
            if(hz>=60)
            {
                P2OUT |= BIT6;
            }
            else
            {
                P2OUT &= ~BIT6;
            }
            flag = 0;
        }
    }
}