HTTP POST request problem

Hi everyone! I have a problem with HTTP request library. I use this code:

import http.requests.*;

import java.net.*;
import java.io.*;
import java.util.*;

String API="myApi"; // Api code
String answer="My answer"; // answer text
String messageTo="1111111"; // example integer
String urlAnswer = URLEncoder.encode(trim(answer)); // encode answer string
PostRequest post = new PostRequest("https://"+"api.telegram.org/bot"+API+"/sendmessage?chat_id="+messageTo+"&text="+urlAnswer);
post.send();

and status monitor show me this error message:

java.lang.NullPointerException
    at http.requests.PostRequest.send(Unknown Source)
    at sketch_160109a.setup(sketch_160109a.java:33)
    at processing.core.PApplet.handleDraw(PApplet.java:2373)
    at processing.awt.PSurfaceAWT$12.callDraw(PSurfaceAWT.java:1523)
    at processing.core.PSurfaceNone$AnimationThread.run(PSurfaceNone.java:316)

But GET request work perfect.

Can somebody explain me how I fix this problem?

I use Processing 3.0 on MacOS 10.9.5