Lpc2000

Hi all,
       I am trying to the external interrupt 3 of lpc2138 to invoke
the trackball routine. But the controller is not responding. The
following is the code i am using.

static void __attribute__ ((interrupt("IRQ"))) ExtInterrupt(void)
{
	VICVectCntl4 = (0 << 5)| VIC_EINT3;
	 //PCON=0x00;
	 //PCONP = 0x001817BE;
	 time=0;
	 init_trackball();
	 EXTINT=0x08;
	 VICVectAddr = 0x00000000;
}
void enableEXTinterrupt(void)
{
	PINSEL1 |= 0x20000000;
	//INTWAKE = 0x0008;
	EXTMODE  = 0x08;
	EXTPOLAR = 0x00;
	VICVectAddr4 =(unsigned int)ExtInterrupt;
   	VICVectCntl4 = VIC_ENABLE | VIC_EINT3;   
}

Am i missing anything? Advanced thanks for any suggestions.

Thanks & regards,
Mohan