printf function with Realview Compiler

I have problem when use printf function in Keil uvision when select Realview Compiler ( Not Keil CARM Compiler ) . it can compile ( not have error ) but not have any response send to serial port.

system = LPC2103 + 12.000MHz + RealView MDK-ARM 3.03q Evaluation

#include <LPC2103.H>
#include <stdio.h>
void init_serial0 (void);

int main(void)
{

init_serial0(); printf("Hello LPC2103 TEST UART-0\n");

while(1);
}

void init_serial0 (void)
{ PINSEL0 |= 0x00000005; U0LCR = 0x83; U0DLL = 97; U0LCR &= 0x7F;
}

But when i write sendchar , sendstr and sendhex functions same MCB2103 Blink Sample code. it work !!

http://www.keil.com/support/man/docs/mcb2103/mcb2103_examples.htm

..thank you very much