ORA-42682
Either the @LINK directive for 'string' table is not specified, or it does not have FROM or TO parameters specified for joining the 'string' and 'string' tables using non-key columns.
Cause
Either the @LINK directive is not being used or the @LINK directive has only one parameter out of FROM and TO.
Action
Specify both FROM and TO parameters in the @LINK directive to create a join based on non-key columns.