The current field must match the join key <name> in the table that serves as the 'one' side of one-to-many relationship. (Error 3341)

You have tried to enter a value into the join field in the many-only table of an outer join with no corresponding value in the join field of the "one" side table.

The message includes the following instruction: Enter a record in the "one" side table with the desired key value, and then make the entry with the desired join field in the "many-only" table.