It's not an error. If you have any other alt on the same home world as your FC character, you *cannot* bid in the lottery on any character *but* the alt you own a personal house on.

And that character must be in the FC your other character owns. And they have to have been in the FC for 30 days.

If you have an FC plot on 1 character and a personal plot on another, I don't know if you can bid at all :/