Thread_Coap_MultiBoard more steps to enable traces over uart ?

Hi everyone,

I started to work with the "Thread_Coap_MultiBoard" example , all work fine , but now i want to display the traces over RS232.

4) Activate the traces if necessary: 
 =====================================
 If you want to get the traces in real time, you can connect an HyperTerminal 
 via an UART RS232 cable using the following connections: 
 RXD: CN10(Pin35) 
 TXD: CN10(Pin37)
 
 
For the traces, the UART must be configured as follows: 
 - BaudRate = 115200 baud 
 - Word Length = 8 Bits 
 - Stop Bit = 1 bit
 - Parity = none
 - Flow control = none
 
 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */

app_conf.h

 * Note : Refer to utilities_conf.h file in order to details
 * the level of traces : CFG_DEBUG_TRACE_FULL or CFG_DEBUG_TRACE_LIGHT
 *****************************************************************************/
#define CFG_DEBUG_TRACE 1

following the readme file the traces should be already enabled, but i got nothing in the terminal, so maybe there is more steps to achieve this ?

regards,

Pierre