Nodejs Mikael's request module proxy returns "Invalid Authentication"

Here is the scenario. I am using Mikael's request module for getting a web page content (HTML or XML). Now it is working okay without using the "proxy" parameter. But as soon as I provide the "proxy" parameter and put my proxy server (say http://myproxy.com:8008) it stops and returns Invalid Authentication

I have used the same proxy in a PHP script using CURLOPT_PROXY parameter which is working fine but on nodejs the "request" module is expecting some kind of authentication. Here is some of the code snippet I am using:

request({
    jar: true,
    headers: request_headers,
    url: "http://www.osnews.com",
    proxy: "http://myproxy.com:8008"
  }, function(error, response, body){
      console.log(body);
  });

Any help would be appreciated. Thanks in advance