Replies not listed by Custom View but new forum topics are

Hi all,
I have created a custom view to aggregate new content or updated content on a small site but I'm having a problem getting replies to a forum topic to be listed in the view, any replies to an existing topic are not being picked up but if I create a new topic that pops up.

My custom view has the "Forum Topic" node type included but how do I get the forum replies to be listed as well?