You probably need to wait till eBay actually makes your listing live. That can take 30min or 8 hours. This all depends on how busy they are. Once it goes live they will let you edit it. So keep trying bud.
Ya, when you post from Auctiva, you can go to your eBay page and you will see it there, you can even click on it and it will show as if it was on eBay live.. however it is not.. that simply means eBay has it in the buffer.
Since you cancelled the auction, then I would simply make your changes in Auctiva and post again.
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