Castling O-O

I am playing Black in a Chess960 game.

My King is on f8.  A Rook is on h8.  g8 is empty.

I want to castle O-O to the Kingside.  My King should end up on g8 and

my Rook should end up on f8.  I can't seem to get them to do this.

It will accept my King moving one square left BUT not the Rook two

squares to the right.   HOW DO i MAKE A CASTLING MOVE...O-O HERE?

Thank you.

I think you drop the king onto the rook.

Try clearing e8. Maybe that would work.

That's right

Yes - ivandh has it right.  Doesn't make any sense however.

Seems that dropping the Rook onto the King would be the way to do it because that is where the Rook will end up...  this is a strange site sometimes...

Thanks guys.

Castling is considered a king move, which is probably why you drop the king onto the rook ?