我的代码怎么了？在执行这些行时，我从redshift得到一个错误。

SELECT
COUNT (
        DISTINCT (
            CASE
                WHEN EXISTS(
                    (
                        select
                            1
                        from
                            (
                                select
                                    ci.order_no,
                                    count(ci.booking_location_id) as cnt
                                from
                                    oms_core_inventory_booking_detail ci
                                group by
                                    ci.order_no
                            ) cibd
                            where cibd.cnt > 1
                            and co.order_no = cibd.order_no
                    )
                ) THEN co.order_no
                else NULL
            END
        )
    ) AS "SP受注数"
from
table co

我犯了这样的错误
由于内部错误，不支持这种类型的相关子查询模式
谢谢你的帮助。
萨利赫