Hello,
Have you created custom store catagories for your ebay store? If so, then you need to synch those with your Auctiva account. Go to My Account, click on the My Account tab, then click on ebay Settings, and then click on Update Store Catagories from ebay.
Then, as you create a listing, you will be able to select your store catagory in which to have the listing appear.
Hope this helps.