Teensy LC Keyboard Problem

At this page you write:
https://www.pjrc.com/teensy/td_download.html
"Version 1.08... Add function keys F13 to F24 to USB Keyboard"

I have tried to use the function it does not work.
Where I 'm wrong ?

#include <Bounce.h>
Bounce button0 = Bounce(0, 10);
void setup() {
pinMode(0, INPUT_PULLUP);
}
void loop() {
button0.update();
if (button0.fallingEdge()) {
Keyboard.set_key1(KEY_F13);
Keyboard.send_now();
delay(1000);
Keyboard.set_key1(0);
Keyboard.send_now();
}
}