Chat messages don't get transferred

I embedded chat into my dashboard.
When I open it up, and write a line, I get in on my UserEcho dashboard.
But when I'm replying to it, it doesn't show. I do see that userecho.com/http-bind gets resolved, and my reply message is in it, but it doesn't appear in the chat window.
After this, the connection breaks, and whatever I write from the dashboard, doesn't show on the agent interface, and vice versa.

The only way I can make it work is when I reload the page. Then I see the chat window.

Is use the following script to initiate the UserEcho module:

var _ues = {
    host:'reevio.userecho.com',
    forum:'44129',
    lang:'en',
    tab_show:false
};

(function() {
    var _ue = document.createElement('script'); _ue.type = 'text/javascript'; _ue.async = true;
    _ue.src = ('https:' == document.location.protocol ? 'https://' : 'http://') + 'cdn.userecho.com/js/widget-1.4.gz.js';
    var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(_ue, s);
})();