Apc 220 Wireless module don't working

i bought a apc220 module and i create a program that turn on a led when i write b and turn off when i write c in serial window.
i try the program with usb cable and work it then i try the program with the wireless module but didn’t work.

int val = 0;
int ledPin = 13;
void setup()

void loop()
  val = Serial.read();
  if (-1 != val) {
   if ('A' == val || 'a' == val) Serial.println("Segnale ricevuto");
   else if ('B' == val || 'b' == val) digitalWrite(ledPin, HIGH);
      else if ('c' == val || 'C' == val) digitalWrite(ledPin, LOW);

how i fix it??

Im a bit lost here.
Where is the other radio module.
You need 2 , one to transmit from and the 2nd to receive .
Those modules are 1/2 duplex, they can send or receive , but not do both at the same time.

the other module is attached to the computer and there is not in the picture.
is there a way to know if the modules work without sending signals from the computer with a single arduino?
if I wanted to stick a camera I can not use the form to send the pictures and at the same time send commands from the computer to control the various components?