Nothing I can readily spot as a problem. Nice plate.
What is the category for listing?
Do you have a Subtitle on the listing that might be objectionable?
Are you listing to US site?
Are you doing Buy-It-Now and meet the minimum requirements/qualifications to use BIN and that info (if you just qualified) is updated on the Auctiva account?
The Auctiva Support folks can probably give you an exact cause, if you enter a Support Case (see HELP link at top of page).
If you are in a rush, you could try posting it directly on ebay to get a more immediate, definitive error on the cause.
Danno