LPC3250 IRQ_HANDLER HELP

Hi Please Help me out for interrupts on LPC3250. How to enable interrupt handler.my program like below

TIMCLK_CTRL1|=0x08;      // Enable timer clock
T1CTCR          = 0x00;         //use as a timer
T1TCR           =0x01;          // enable timer
T1MCR           =0x00000018;    // match reg 1
T1MR1           =0x00000000;    // reset and Interrupt

And in LPC32x0.s the interrupt handler enabled like this

                                ;PRESERVE8 {FALSE}
                                IMPORT  IRQ_Handler

Reset_Addr      DCD     Reset_Handler
Undef_Addr      DCD     Undef_Handler
SWI_Addr        DCD     SWI_Handler
PAbt_Addr       DCD     PAbt_Handler
DAbt_Addr       DCD     DAbt_Handler
                DCD     0               ; Reserved Address
IRQ_Addr        DCD     IRQ_Handler
FIQ_Addr        DCD     FIQ_Handler

Undef_Handler   B       Undef_Handler
SWI_Handler     B       SWI_Handler
PAbt_Handler    B       PAbt_Handler
DAbt_Handler    B       DAbt_Handler
;IRQ_Handler     B       IRQ_Handler
FIQ_Handler     B       FIQ_Handler

My interrupt routine as below

void IRQ_Handler(void)__irq
{
send_data('D'); // for uart5
P2_OUTP_CLR|=0x00001820; // checking for led glow

        if((MIC_SR&0x00020000)==0x00020000)
        {
        send_data('C');
          T1IR          |=0x01; // T1 Interrupt

          //timer1();

        }
        return;
}

program does not entering into IRQ_Handler
Please Help me out.
Thanks in advance.