mongodb node driver events not working

gistfile1.js

var mongodb = require('mongodb');                                               
var ReplSet = mongodb.ReplSet;                                                  
var replSet = new ReplSet([                                                     
  new mongodb.Server('localhost', 27018, {}),                                   
  new mongodb.Server('localhost', 27019, {}),                                   
  new mongodb.Server('localhost', 27020, {})                                    
], { rs_name : 'rs0' } );                                                       
                                                                                
//var mongoserver = new mongodb.Server('localhost', 27017, {});                 
var db_conn = new mongodb.Db('test1', replSet, { w : 1 });                      
var db2 = db_conn.db("test2");                                                  
                                                                                
db2.on('close', function () {                                                   
  console.log("db2 close");                                                     
});                                                                             
db_conn.on('close', function () {                                               
  console.log("db1 close");                                                     
});                                                                             
db2.on('error', function () {                                                   
  console.log("db2 error");                                                     
});                                                                             
db_conn.on('error', function () {                                               
  console.log("db1 error");                                                     
});                                                                             
db2.on('timeout', function () {                                                 
  console.log("db2 timeout");                                                      
});                                                                                
db_conn.on('timeout', function () {                                                
  console.log("db1 timeout");                                                      
});                                                                                
db2.on('open', function () {                                                       
  console.log("db2 open");                                                         
});                                                                                
db_conn.on('open', function () {
  console.log("db1 open");                                                      
});                                                                             
db2.on('fullsetup', function () {                                               
  console.log("db2 fullsetup");                                                 
});                                                                             
db_conn.on('fullsetup', function () {                                           
  console.log("db1 fullsetup");                                                 
});                                                                             
db_conn.open(function (err) {                                                   
  if (err) throw err;                                                           
                                                                                
  var col1 = db_conn.collection('test');                                        
  var col2 = db2.collection('test');                                            
                                                                                
  var testData = { value : "something" };                                       
  col1.insert(testData, function (err) {                                        
    if (err) throw err;                                                         
    col2.insert(testData, function (err) {                                      
      if (err) throw err;                                                       
      db2.close();                                                              
      console.log("done");                                                      
    });                                                                         
  });                                                                           
});