I have tried using the widget and short code but no tags are showing.
I've tried different settings in the widget to see if I was putting something there incorrectly. I tried showing 200 tags and then only 20 tags.
If you go to http://e-business.ie/omadaccts/accounts-preparation/ you will see two areas for tag clouds on the right. The 2D Tag Cloud widget is being used for "Articles by Topic" and the default tag could widget is being used for "Articles & Resources by Topic" so you can see that there are tags being used on the site.