You need to also add the genus Hyacinthus.
Dave, when I tried it the same way with just the common name and cultivar name, I get this message at the top "Important: Don't add quotes around the names. The system will add those automatically when appropriate."
I didn't have any quotes but it seems to default to that way, at least I assume that's what's going on. Maybe adding that the genus needs to be filled in too would prevent this error.