Room Occupancy Modifier not recognised

My room occupancy modifier is not being applied when searching and booking rooms.
I currently have two database tables called hotel_booking_occupancy_modifiers and hotel_booking_room_occupancy_modifiers
Table hotel_booking_occupancy_modifiers has two rows, both are the occupancy modifiers as submitted. All good.
Table hotel_booking_room_occupancy_modifiers is empty.

The function:

function hotel_booking_occupancy_modifier_load($id) {
  return db_fetch_object(db_query('SELECT *
                                  FROM {hotel_booking_occupancy_modifiers}
                                  WHERE hbomid = %d', $id));
}

picks from the second, empty table.

Is this a bug or have I had some issues moving from beta4 to dev versions and messed up an upgrade along the way.

Relatively new so suspect its at my end.

Thanks, Matt