MQTT newbie troubles

ok. this problem solved by setting options when 'create'

but i have next one. i can see messages in debug, but mqtt module give me error again

function mqttRun(){
  var server = 'my_broker';
  var options = {
          keep_alive: 60,
          port: my_port,
          clean_session: my_port,
          client_id: "my_id",
          username: "my_user",
          password: "my_pass",
          protocol_name: "MQTT",
          protocol_level: 4,
  };
  var mqtt = require("MQTT").create(server, options); // changes here
    mqtt.on('connected', function() {
    mqtt.subscribe("/test");
  });
   mqtt.on('publish', function (pub) {  // this place throw error
    console.log("topic: "+pub.topic);
    console.log("message: "+pub.message);
  });

  mqtt.connect();

}

Uncaught Error: Field or method "topic" does not already exist, and can't create it on undefined