Communication coordinator API and end devices AT problem on Arduino

Hello,

I made the purchase the book “Home Automation with Arduino” in French version (Arduino pour la domotique)

But I am confronted with one of my XBee configuration problem
in chapter 8 of the book

I use:
1 arduino uno
1 XBee shield
2 xbee S2-004 XB24-Z7WIT revK
1 exbee explorer
1 Pir

Same of the book config

I realized my tests on a PC and MAC
I used different USB cables
I used xbee explorer different
I used different XBEE
and even different arduino

XCT-U for programming the XBee

I have an XBee ZB-XB24 configured with API function coordinator and firmware 21A7
here’s the setup:

<?xml version="1.0" encoding="UTF-8"?> XB24-ZB_21A7.xml 2712 FFFF 3 0 FF 0 FFFF 0x20 1E 0 FF 30000 3C 0 3 4 1 0 0 3 0 0 1 0 2 0 20 1 1 0 0 0 0 1 1 0 0 1FFF 0 28 1 0 0 0

and XBee ZB-XB24 in with AT function end devices and firmware 28A7
here’s the setup:

<?xml version="1.0" encoding="UTF-8"?> XB24-ZB_28A7.xml 2712 FFFF 3 0 FF 0 0 0 0x20 30 0 30000 3C 0 3 E8 E8 11 4 1 0 0 3 0 0 3 1 0 64 3E8 2B 4 1388 20 1 0 0 1 0 0 0 0 1 1 0 0 1FFF 0 28 1 0 0 0

here is the source code for Arduino:

// Libraries
#include <SPI.h>
#include <aREST.h>

// Motion sensor ID
char * xbee_id = “2”;

// Create ArduREST instance
aREST rest = aREST();

void setup() {

// Start Serial

Serial.begin(9600);

// Give name and ID to device
rest.set_id(xbee_id);

rest.set_name(“motion2”);
}
void loop() {
// Handle REST calls
rest.handle(Serial);
}

The FTDI drivers are installed perfectly on PC and MAC

When I make a discovery of XBEE network XCT-U, everything is OK and everything is discovered . no problem.

But when I want to test the project
using either coolterm, TeraTerm, the serial monitor IDE Arduino ,when entering /id, nothing is returned.
Same for /Digital/8/
But when I change my coordinator API in COORDINATOR AT it works.

I confess to not understanding where is the problem.
If you could look a bit my problem, that allow me to advance in my work

Kind regards and thank you for your response

Didier