Simbunch Answers won't let me create any category. Whenever I try to create a category I get an error.

Simbunch Answers won't let me create any category. Whenever I try to create a category I get the following error: Invalid `parent_id` [0] in SIMAnswersTableCategories::check()
Even if I try to click on a link that creates sample categories, while it says the creation was successful, however not even a single category would have been created.