The Discussion Web Part in SharePoint has always been a bit quirky. It doesn’t act like most other discussion applications and can often confuse users.
One specific confusing "feature" is this. When you start a discussion, the Subject is visible as a link in the Web Part. If you click on the Subject, the same site will reload, and the Discussion Web Part will show this message:
There are no items to show in this view of the "[Discussion Name]" discussion board. To create a new item, click "Add new discussion" below.
What does that mean? Didn’t you just create a discussion thread? What SharePoint has done is "open up" your existing discussion thread in the Web Part. Since no one has replied to your post yet, there are no items to show. This isn’t what most people expect.
The best way to deal with this is to have your users drill into the Discussion Web Part by clicking on the Web Part title and look at things there.