unable to read data on Interrupt

I have ALtera DE2_115 Board having Cyclone IV E,

static void *handle_load_interrupts(void* context, alt_u32 id)
{
edge_capture = 0;
volatile int* edge_capture_ptr = (volatile int*) context;
*edge_capture_ptr = IORD_ALTERA_AVALON_PIO_EDGE_CAP(LOAD_BASE);	
//Store the value in the LOAD edge capture register in *context
IOWR_ALTERA_AVALON_PIO_EDGE_CAP(LOAD_BASE,0);     //Reset the LOAD edge capture register
IORD_ALTERA_AVALON_PIO_EDGE_CAP(LOAD_BASE);		//Read the PIO to delay ISR exit. this is done to prevent a spurious
  }
/* Enable all 4 button interrupts. */
IOWR_ALTERA_AVALON_PIO_IRQ_MASK(LOAD_BASE, 0x01);
/* Reset the edge capture register. */
IOWR_ALTERA_AVALON_PIO_EDGE_CAP(LOAD_BASE, 0x0);
alt_ic_isr_register(LOAD_IRQ_INTERRUPT_CONTROLLER_ID, LOAD_IRQ,handle_load_interrupts, edge_capture_ptr, 0x0);
---------------------------------------------------------------------------
---this is the receiver code who read data from external bus "DATA"---
do
{
if( edge_capture)		//w.r.t. clock or LOAD Pulse from "sync_detect"
{
ImgBuff = IORD_ALTERA_AVALON_PIO_DATA(DATA_BASE);
Count++;
edge_capture = 0; //reset generated LOAD interrupt
}
  	if(Count == 640-1)	//check end of data -->640
  	{
	  	Count = 0;		//Point to Start of data
		LPktCount++;	//Increment Count
  	}
}while(LPktCount != (400-1));