Configuring Ejabberd to use an external component (with XEP-0114)

I'm developing a system that uses XMPP for real-time communication between a mobile app and my server. It's purpose is different to instant-messaging, so I'm trying to develop an external component that processes the XMPP messages and send out new ones.

I have been attempting to use SleekXMPP (https://github.com/fritzy/SleekXMPP) to create an external component (following XEP-0114).

However I'm having difficulty communicating between my Ejabberd server and the component. I've been trying to build a simple Echo component (it repeats what users send to it) just to learn how to make and connect a component in Ejabberd.

I suspect the problem lies within the component I've created. I've added this to 'LISTENING PORTS' in ejabberd.cfg file (and then restarted ejabberd).

The component is a Python script running on the same machine as the server. Is this all I need to do in Ejabberd to add the echo component?

(The script it is quite similar to the one here: https://github.com/legastero/xmpp-tdg/blob/master/code/CheshiR/SimpleCom...)

I am unable to add echo.mydomain.com when logged into the server from an XMPP client - it says adding contact but it does not show up in the roster on the client.

Is there anything non-obvious about setting up an external component to work with Ejabberd, something I may have missed? Or do you know of a simple echo bot component I could use for testing?

I apologize if my question is vague, I am beginner developer of Ejabberd, please let me know what areas should have more detail.

Thank you.