Unanswered forum threads

I have set up "Trending Groups" in my forum. I have also set up a list down the side using "Forum-Thread list" widget. Within this widget i have selected to only show unanswered posts. The idea is to encourage members to get involved in the conversation or reply to a fellow member who is awaiting a response, however, it isnt working. It's pulling through posts that have been replied to. Is there something I can do so that only posts/threads that have no reply/answer are pulling through?

                                     

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