Android ADK Blinking example not blinking sometimes

I have arduino uno connected with itead usbshield. I am receiving the data from android phone and it blinks only when i open serial monitor otherwise it is not. How to blink it independently. Is there any way it relates with opening serial monitor...?

I use pin 13 for blinking it... Please guide me in to this...

This is the code...

void loop()
  if(adk.isReady()) {
    uint8_t msg[1];
    uint16_t len = sizeof(msg);
    uint8_t rcode = adk.RcvData(&len, msg);
    if(rcode && rcode != hrNAK)
      USBTRACE2("Data rcv. :", rcode);
    if(len > 0) {
      Serial.print(F("\r\nData Packet: "));
      digitalWrite(LED,msg[0] ? HIGH : LOW);
    digitalWrite(LED, LOW);

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