Assuming you meant Buyee, I had a similar problem about a year ago. I asked Buyee at the time and this was their response:
“Regarding the error you have experienced, we have confirmed the reason and unfortunately Buyee can not purchase this item from the seller since this item belongs to a new Yahoo! JAPAN Auction's purchase function.
For future bids/purchases in Yahoo! JAPAN Auction, please refer below to how to confirm which items can not be purchased at the moment:
1. The Buyee page shows "Win now for Buyout price".
2. You click on "View on Yahoo! JAPAN Auction", if the orange button in the Yahoo page reads:
購入手続きへ (Proceed to ordering)
It means is an item that is not available for purchase on the Yahoo! JAPAN Auction site
We are working on implementing this new purchase method on our Yahoo! auction system. However, at the moment, we are unable to confirm when this will be available in Yahoo! Auction.”