Create table with USING clause not working

I was trying to create a bakcup of some data before a did a mass update and thoguht this would work:

create table mylib.FILE_BACKUP as
(
select
rthd, opseq, opdsc
from
amflibp.rtghdr join
amflibp.rtgopr using (STID, RTID, RTVR)
) with data
;

The underlying SQL for the select statement works, but the create table causes the following errors:

SQL State: 58004
Vendor Code: -901
Message: [SQL0901] SQL system error. Cause . . . . . : An SQL system error has occurred...The previous message identifier was MCH3601. Internal error type 6101 has occurred...

MCH3601: Pointer not set for location referenced.

When I change my select staement to use on criteria in the join it works just fine.

create table mylib.FILE_BACKUP as
(
select
rthd, opseq, opdsc
from
amflibp.rtghdr A join
amflibp.rtgopr B on A.stid=B.stid and A.rtid = B.rtid and A.rtvr = B.rtvr
) with data
;

Does anyone know why the USING clause doesn't work with the "CREATE TABLE as (select statement) with data"?
We are at 6.1.

-Tom Stieger
California Fine Wire