Hi Bruno,
I don't know of any limit on outer joins (except the entire SQL statement can't be more than 8,192 bytes).

The error you are experiencing is due to the VFP limit of queries within queries.

select * from table1 where field1 in ;
(select field1 from table2 where field2 in ;
(select field1 from table3))

VFP only allows one level of subquerying. You can not go two or more levels deep. Check the complexity of your outer joins and see if you in fact have too many levels. You may have to process some of the queries into temporary cursors and then use those itermediate tables in processing your final query.

HTH,
Larry