Interrupt is not working?

Hi am new to this forum.I have recently ordered a "free" KEIL evalution software CD for ARM development tools.I am working on LPCE2214 OLIMEX board. Am able to toggle a PORT pin and also on TIMER and serial port in "polling" mode. But when I enable ISR funstions using VIC,my program in not jumping to ISR.but in debug mode i could see the jump to ISR. also I have DefaultISR in my code.here am attaching my code with this mail.
// This program is created for LPC-E2214 board
#include "lpc22xx.h"

#define OSCILLATOR_CLOCK_FREQUENCY 14745600 //in MHz
#define PLOCK 0x400 //in MHz


void Initialize(void);
void feed(void);
void UART0Initialize(unsigned int baud);
void UART0WriteChar(unsigned char ch0);
unsigned char UART0ReadChar(void);
unsigned char UART0ReadChar_nostop(void);
unsigned int processorClockFrequency(void);
unsigned int peripheralClockFrequency(void);

void tc0(void)__irq;
static void DefDummyInterrupt(void)__irq;

void init_timer(void);
void InitVIC(void);

long volatile timeval;

void wait (void) /* wait function */
{
unsigned long i;
i = timeval;
while ((i + 10) != timeval); /* wait 100ms */
}



int main()
{
/**** VARIABLES ****/
unsigned char ch0 = 0x0;
unsigned char ch1 = 0x0;
long i=0;

/**** INITIALIZATION ****/
// Frequency initialization
Initialize();
// UART initialization
UART0Initialize(9600);

init_timer();
InitVIC();


while(1)
{

UART0WriteChar('3');
wait();

UART0WriteChar('2');
wait();
}

}


void Initialize(void)
{

// Setting Multiplier and Divider values
PLLCFG=0x23;
feed();

// Enabling the PLL */
PLLCON=0x1;
feed();

// Wait for the PLL to lock to set frequency
while(!(PLLSTAT & PLOCK)) ;

// Connect the PLL as the clock source
PLLCON=0x3;
feed();

// Enabling MAM and setting number of clocks used for Flash memory fetch (4 cclks in this case)
MAMCR=0x2;
MAMTIM=0x4;

// Setting peripheral Clock (pclk) to System Clock (cclk)
VPBDIV=0x1;

}


void feed(void)
{
PLLFEED=0xAA;
PLLFEED=0x55;
}

/* Setup the Timer Counter 0 Interrupt */
void init_timer (void) {
T0MR0 = 149999; // 10mSec = 150000-1 counts
T0MCR = 3; // Interrupt and Reset on MR0
T0TCR = 1; // Timer0 Enable
VICVectAddr0 = (unsigned long)tc0; // set interrupt vector in 0
VICVectCntl0 = 0x20 | 4; // use it for Timer 0 Interrupt
VICIntEnable = 0x00000010; // Enable Timer0 Interrupt // Timer0 Enable
}

/* Timer0 Compare-Match Interrupt Handler (ISR) */
/* Timer Counter 0 Interrupt executes each 10ms @ 60 MHz CPU Clock */
/* Timer Counter 0 Interrupt executes each 10ms @ 60 MHz CPU Clock */
void tc0 (void) __irq
{
++timeval;
T0IR = 1; // Clear interrupt flag
VICVectAddr = 0; // Acknowledge Interrupt
}
void DefDummyInterrupt(void)__irq
{
;
}
void InitVIC()
{
VICDefVectAddr = (unsigned long)DefDummyInterrupt;
}


/**** UART0 ****/
void UART0Initialize(unsigned int baud)
{
unsigned int divisor = peripheralClockFrequency() / (16 * baud);

U0LCR = 0x83;


//devisor
U0DLL = divisor & 0xFF;
U0DLM = (divisor >> 8) & 0xFF;
U0LCR &= ~0x80;

//set functionalite to pins: port0.0 -> TX0, port0.1 -> RXD0
PINSEL0 = PINSEL0 & ~0xF | 0x5;
}

void UART0WriteChar(unsigned char ch0)
{
//when U0LSR_bit.THRE is 0 - U0THR contains valid data.
while ((U0LSR && 0x20) == 0);
U0THR = ch0;
}

unsigned char UART0ReadChar(void)
{
//when U0LSR_bit.DR is 1 - U0RBR contains valid data
while ((U0LSR && 0x01) == 0);
return U0RBR;
}
unsigned int processorClockFrequency(void)
{
//return real processor clock speed
return OSCILLATOR_CLOCK_FREQUENCY * (PLLCON & 1 ? (PLLCFG & 0xF) + 1 : 1);
}

unsigned int peripheralClockFrequency(void)
{
//VPBDIV - determines the relationship between the processor clock (cclk)
//and the clock used by peripheral devices (pclk).
unsigned int divider;
switch (VPBDIV & 3)
{
case 0: divider = 4; break;
case 1: divider = 1; break;
case 2: divider = 2; break;
}
return processorClockFrequency() / divider;
}

Please look into this and It would be a great help for me as i have been trying for it from past 2 weeks.
I think, abviously iam missing some things. I have not changes any things in startup.s file.
please guide me.appreciate your help.

Thanks