Using App Inventor To Control Motor Shield Through Bluetooth

Hello, sory for reopen this topic...
But what did you do to it works as well? I'm trying to do a LED control, here is the code:

#include <SoftwareSerial.h>

#define LED_1       4
#define LED         3

SoftwareSerial bluetooth(6, 7); // RX, TX

void setup()  
{
  Serial.begin(38400);
  bluetooth.begin(38400);
  pinMode(LED, OUTPUT);
  pinMode(LED_1, OUTPUT);
}

void loop()
{
  digitalWrite(LED_1, HIGH);
  char letra;
  if (bluetooth.available()){
    letra = bluetooth.read();
    if (letra == 'A'){
      digitalWrite(LED, HIGH);
    }
    if (letra == 'a'){
      digitalWrite(LED, LOW);
    }  
  }
}

PS.: I'm using BT Shield IteadStudio V2.2