Hi Mdhmf3,
Thanks for posting your question here. If you are receiving a message indicating that you must select a "leaf category" when listing through Auctiva, I suspect that you most likely selected an eBay store category for the listing that has subcategories within it.
For example, if you have a store category that is filed under Shirts > Summer > Tank Tops and you chose Shirts > Summer as your eBay store category, you would receive a message to this effect and would just have to choose Shirts > Summer > Tank Tops to post the listing successfully.
I hope this helps. If you need any further assistance with this after reviewing this information, please contact our Customer Support Team by mousing over the “Help” tab within your account and selecting the “File Support Case” option.
-Mike