Riak connectivity from Node - node.js

Question

this is probably not a bug but rather a gap in my understanding but putting it here as afraid havent been able to find a way so far. Appreciate if you can provide your inputs please.
I'm trying to connect to my Riak cluster (hosted on AWS) of 3 nodes via two options - 1) Using an ejabberd server, and 2) using a Node server.
Connecting from the ejabberd server is successful after I put the hostname and port in the ejabberd configuration, but when I use a simple Node server (code below), I get the "Error: No RiakNodes available to execute command." error. Am I missing out on something here please - I can confirm that the 3 nodes are indeed up with Riak running? Note that if I dont do the client ping on the nodes, the server doesnt throw any error, so it is probably got to do with how pings are handled. The same server (without the ping) gives an ECONNREFUSED error if one of the nodes are brought down. So clearly the connection is going through but not the ping.
Apologize if am missing out on something basic here ... even the firewall settings for the Riak nodes have been set to all inbound, so it is not a case of the ejabberd server having access but not the Node server.
var async = require('async');
var assert = require('assert');
var logger = require('winston');
var Riak = require('basho-riak-client');
logger.remove(logger.transports.Console);
logger.add(logger.transports.Console, {
level : 'debug',
colorize : true,
timestamp : true
});
var nodes = [
'ip-xx-xx-xx-xx:8087',
'ip-xx-xx-xx-xx:8087',
'ip-xx-xx-xx-xx:8087'
];
var client = new Riak.Client(nodes, function (err, c) {
logger.info('Now inside Riak.Client');
// NB: at this point the client is fully initialized, and
// 'client' and 'c' are the same object
});
client.ping(function (err, rslt) {
logger.info('Now entered client.ping');
if (err) {
logger.info('There is an error encountered in client.ping');
throw new Error(err);
} else {
// On success, ping returns true
logger.info('client.ping has resulted in success!');
assert(rslt === true);
}
});