Same error here. Asked support, learned this:
"When previously owned domains are released by the Registry back to the public for open registration, there is a fixed window where they qualify as re-registrations (re-reg). The window starts as soon as the domains are released, or dropped, and ends 23:59 UTC that same day. If a domain is registered within that time frame, it is a re-registration."
I've never heard this term before. The domain I was trying to buy was in fact a drop reg, so this would apply.
Has anyone tried registering a domain that is not a drop reg with this code?