AD 采样不成功

我用的是LM4F120H5QR控制板做实验，使用的是AN1，即PE1口，AD例程如下

int main(void)

 {        unsigned long ulADC0_Value[1];   

         unsigned long addr;   

         SysCtlClockSet(SYSCTL_SYSDIV_10|SYSCTL_USE_PLL|SYSCTL_OSC_MAIN|SYSCTL_XTAL_16MHZ);   

           SysCtlPeripheralEnable(SYSCTL_PERIPH_ADC0);   

           SysCtlPeripheralEnable(SYSCTL_PERIPH_GPIOE); 

           GPIOPinTypeADC(GPIO_PORTE_BASE,GPIO_PIN_2);
           SysCtlADCSpeedSet(SYSCTL_ADCSPEED_1MSPS);

           ADCSequenceConfigure(ADC0_BASE,3,ADC_TRIGGER_PROCESSOR,0);

           ADCSequenceStepConfigure(ADC0_BASE,3,0,ADC_CTL_CH1|ADC_CTL_IE|ADC_CTL_END);  

           ADCSequenceEnable(ADC0_BASE,3);   

           ADCIntClear(ADC0_BASE,3);  

             while(1)      

                   {        

                             ADCProcessorTrigger(ADC0_BASE,3);        

                              while(!ADCIntStatus(ADC0_BASE,3,false))       

                                   {

                                   }        

                             ADCSequenceDataGet(ADC0_BASE,3,ulADC0_Value);       

                             addr=ulADC0_Value[0];     

                             SysCtlDelay(SysCtlClockGet()/12);   

                     }

  }

但是程序总在    while(!ADCIntStatus(ADC0_BASE,3,false))       过不去，不知道是什么原因呢？