Problem with sending data from labview to arduino

Hi guys.

my english it's not very good,sorry about that.

I programing arduino uno with this code and I sending data with labview(2011) to arduino but itdoes notwork well.

This means when labview is running,LED on arduino is turn on and turn off and when labview became stop, LED is turn on and turn off continuously while it must remain off.

please help me.

char in=0;  
void setup() {
Serial.begin(9600);
pinMode(13 , OUTPUT);
             }

void loop() {
if (Serial.available() > 0)
    in = Serial.read();
if(in=='2'){   
    digitalWrite(13, HIGH);
        delay(100);
    digitalWrite(13, LOW);
        delay(100);               
          in=0;
           }