mongoose keep having Error: unauthorized for a simple collection.find()

Trying for about 3 hours to translate a db.collection('collection-name').find() to mongoose but never seem to be able to auth the find().

Stack Trace:

Error: unauthorized db:parks ns:parks.parkpoints lock type:0 client:127.2.132.1
at Promise.error (/var/lib/user/app-root/runtime/repo/node_modules/mongoose/lib/promise.js:88:38)
at cb (/var/lib/user/app-root/runtime/repo/node_modules/mongoose/lib/query.js:1454:29)
at /var/lib/user/app-root/runtime/repo/node_modules/mongoose/lib/utils.js:408:16
at /var/lib/user/app-root/runtime/repo/node_modules/mongodb/lib/mongodb/cursor.js:146:30
at /var/lib/user/app-root/runtime/repo/node_modules/mongodb/lib/mongodb/cursor.js:188:32
at /var/lib/user/app-root/runtime/repo/node_modules/mongodb/lib/mongodb/cursor.js:504:39
at Cursor.close (/var/lib/user/app-root/runtime/repo/node_modules/mongodb/lib/mongodb/cursor.js:776:5)
at [object Object].<anonymous> (/var/lib/user/app-root/runtime/repo/node_modules/mongodb/lib/mongodb/cursor.js:504:21)
at [object Object].g (events.js:156:14)
at [object Object].emit (events.js:88:20)
npm info Sample-App@1.0.0 Failed to exec start script

Connection.once('open') event is hit, so connection shouldn't be the problem, but I keep hitting the error at console.log("find() error");.

Anyone has any clue on what's going on?

• Database name: parks
• Collection name: parkpoints
• Mongoose version: 3.3.1
• Mongodb version: 2.2.0

I double-checked the values for user, pass, host, and port, those shouldn't be the source of problem.

self.connectDb = function(callback){
mongoose.connection.on('error', function(err){
  console.log("connection error");
  throw err;});
mongoose.connection.once('open', function(){
  callback();
  self.Parkpoint=mongoose.connection.model('Parkpoint', 
           new Schema({ Name: String, pos: [Number]})); 

  self.Parkpoint.find().exec(function(err, names) {
    if(err){
      console.log("find() error");
      throw err};
     console.log("names: "+names);
    res.header("Content-Type:","application/json");
    res.end(JSON.stringify(names));
});


});

var dbUri = 'mongodb://'+self.dbUser+':'+self.dbPass+'@'+self.dbHost+':'+self.dbPort+'/parks';
console.log(dbUri);
mongoose.connect(self.dbHost, "parks", self.dbPort, {user:self.dbUser, pass:self.dbPass});
};