Amazon web services - Connect Elastic Beanstalk with ElasticCache

I have a node.js application running on an Amazon EBS environment

in my app code I create an instance of memcached (my elastic cache) like this:

var Memcached = require('memcached');
var memcached = new Memcached('my-elastic-cache-configuration-endpoint:11211'); 

In creating my ElasticCache cluster I used the security group of the EC2 instance running my EBS app. And in that security group I have allowed inbound access on port 11211 as described here: Amazon ElasticCache Step 3: Authorize Access

However my memcached elastic cache is still not accessible from my app.

I have tested it locally to make sure the code is alright etc. and everything checks out. Does anyone know what I may be missing?