I have a feeling you selected paired images and you may also have a store bar on the side of your page! Am I correct?
A link to your auction would have been helpful, but lets see what we can do to remedy it
If you have paired pictures rather than stacked,
Open your saved auction in Auctiva , got to your template and select modify template. Choose an option other than paired ( I use vertical)Save this to the listing.
Now the tricky part is you have to open the revise page in eBay and select the HTML box on the editor. remove that HTML and replace it with the revised HTML from Auctiva.
if you have never attempted to work with HTML PLEASE open notepad and save the HTML you have cut from eBay so you at least have the capability of repairing the code if you somehow mess up.
Hope this helps you out!