TCP IP Problem MCB 2300

Hi..

I am working on MCB2300(LPC2387) board.
I have made one application to send and receive data through TCP and the same time I am trying to toggle LEDs connected on port0.
I have used demo code of TCP_listen provided by keil.
The problem is when I run the program leds are blinking but my board could not connect with LAN and if I remove the portion of LEDs from main the board will connect..
But I want to run both at same time..

Below is the main function of my code.

int main (void)
{
        char ia[SENDLEN];
        int ic = 1;
        init ();
        init_TcpNet ();
        GPIOInit( 0, FAST_PORT, DIR_OUT );
        GPIO_Address = 0x00000004;   // port 0.2


    for(ic = 0 ;ic < SENDLEN; ic++)
        {
         ia[ic] = ic+1;
        }

   socket_tcp = tcp_get_socket (TCP_TYPE_CLIENT, 0, 10, tcp_callback);


           while(1)
             {

                   timer_poll ();
                   main_TcpNet ();

                  if(wait_ack == 0)
                  {
                        send_data(ia);
                  }

                  STB1_Channel_Change();
                  Channel_Change_Delay(GPIO_Address);

          }
}

if you want to see code of TCP, you can refer it from the demo codes provided by keil.
I can not paste whole program here. please bear with me.

Any one has any idea about this problem??
Please let me know..

Thanks