SQL & PL/SQL

The following merge sql on Oracle 11g throws "ORA-02070 database does not support semi join in this context".

MERGE INTO ORDERS tgt
USING
(
SELECT C.short_name, C.customer_id
FROM customers C
WHERE customer_id IN ( SELECT distinct customer id FROM orders O WHERE O.order_date > SYSDATE - 3 )
)src
ON ( tgt.customer_id=src.customer_id )
WHEN MATCHED THEN
UPDATE SET tgt.short_name=src.short_name;

Any ideas? This piece of code was working on an earlier version of Oracle 11g.

Thanks,
Anu