Selecting Article categories for listing on a forum

I setup a forum for articles.

For article categories themselves I have One top level category named "Year 2016", and a sub article category to it named "September".

I added an article and picked the sub category "September" to list it in. Also under ARTICLE settings for forums used for listing articles I selected just the "Year 2016" because all articles get listed in that (even if added to a sub-category under it. But when I looked on forum no article thread was listed for discussion and also noticed the article wasn't being displayed on Dashboard either under recent activities.

So next selected no article categories at all for (forum settings), so it pulls from all and that worked creating an article forum topic, also displayed article on Dashboard

Not sure if I should have selected both categories (even sub one) for forum settings. But not sure why even if that was wrong and I should have selected both - why the article still didn't get displayed on Dashboard anyway?

Okay, I get what what you mean. It wasn't pulled from forum before onto recent activities because the sub-cat article was added in wasn't selected as ARTICLE cat for forum to pull from. So no forum topic got created for it which meant nothing got pulled on Dashboard from forum for it.

I just tested selecting both categories to pull from, or selecting none (so it pulls from all) and that worked both times creating a forum topic and listing it on dashboard.