When constructing synchronization parameters to filter rows to be download to a device, if the SQL statement involves two mobile business objects, you must use an "in" clause rather than a "join" clause. Otherwise, when there is a joined SQL statement, all rows of the subsequent mobile business object are filtered out.
For example, you would change this statement:
SELECT x.* FROM So_company x ,So_user y where x.company_id = y.company_id and y.uname='test'
To:
SELECT x.* FROM So_company x where x.company_id in (select y.company_id from So_user y where y.uname='test')