Your screen appears to be blank so there my be a general issue with the wiki itself. The server's log will tell.
If this is not the case that make sure that you do not want do load http content via https. Nowadays browsers block mixed content without the decency of even telling the user that content was blocked. This was the case at the mediawikiwidgets.org
website which I just fixed.
Or you are behind a firewall preventing content to be retrieved from outside.
Apart from that I have not idea that the issue may be. The widget is working on mediawikiwidgets.org