CC3200-LAUNCHXL: Sensor Ultrasonic - CC3200

Hello.
This is my first post here on the forum.
I'm trying to measure the distance with an ultrasonic sensor on the cc3200 board, but I can not. On the serial port and printed are the number 51. Does anyone have any tips?

Ps .: I'm from Brazil and I'm using Google Translate to talk to you. XD
Ps .: I do not know if this is the right place for questions, let me know if I'm in the wrong place.

Thank you!

// Ultrasonic - Library for HR-SC04 Ultrasonic Ranging Module.
// Rev.4 (06/2012)
// J.Rodrigo ( www.jrodrigo.net )
// more info at www.ardublog.com

#include <Ultrasonic.h>

Ultrasonic ultrasonic(45,8); // (Trig PIN,Echo PIN)

void setup() {
  Serial.begin(9600); 
}

void loop()
{
  Serial.print(ultrasonic.Ranging(CM)); // CM or INC
  Serial.println(" cm" );
  delay(100);
}