comparator issues

hi, i'm trying to make the comparator works, following the soc userguide, my code is the following:

void comphandler(void)
{
  GPIOPinIntClear(GPIO_A_BASE,GPIO_PIN_5);
  GPIOPinWrite(GPIO_B_BASE,GPIO_PIN_5,0xff);
}



int
main(void)
{


    SysCtrlClockSet(false, false, SYS_CTRL_SYSDIV_32MHZ);


	
    SysCtrlIOClockSet(SYS_CTRL_SYSDIV_32MHZ);
     

	 
    
    HWREG(0x400D9710) |= 0x20;    	// set PAIEN5 
    HWREG(0x400D9704) |= 0x0;		//PAIRC5=0 : rising edge interrupt
    
    
    

    HWREG(0x400D7024) |= 0x02;		//enable comparator
    HWREG(IOC_PA5_OVER) |= 0x01;	//set PA5 analog
    HWREG(IOC_PA4_OVER) |= 0x01;	//set PA4 analog
   
   
    IntMasterEnable();
	IntEnable(INT_GPIOA);
	
    GPIOPinWrite(GPIO_B_BASE,GPIO_PIN_5,0);

	
    while(1)
    {

	
    }
}


it's a one shot function,just to see if the interrupt works. 
but i have no response, i use pa4 as reference pin and have a trimmer on pa5.

thanks!