Small schema with "Query expression source must be an aggregate" error

test_schema.exp

--    $ ../bin/fedex_plus ../../data/test_schema.exp
--    ../../data/test_schema.exp:34: --ERROR: Query expression source must be an aggregate.
--    Errors in input

SCHEMA test_schema;

ENTITY representation_item
    SUPERTYPE OF (ONEOF (binary_representation_item, compound_representation_item));
    name : label;
--WHERE
  --  WR1 : SIZEOF(using_representations(SELF)) > 0;
END_ENTITY;

TYPE list_representation_item = LIST [1:?] OF representation_item;
END_TYPE;

TYPE set_representation_item = SET [1:?] OF representation_item;
END_TYPE;

TYPE compound_item_definition = SELECT (
    list_representation_item,
    set_representation_item);
END_TYPE;

ENTITY compound_representation_item
    SUPERTYPE OF (ONEOF (point_and_vector, table_representation_item))
    SUBTYPE OF (representation_item);
    item_element : compound_item_definition;
END_ENTITY;

ENTITY table_representation_item
    SUBTYPE OF (compound_representation_item);
WHERE
    WR1 : SIZEOF(QUERY(itet <* SELF\compound_representation_item.item_element |
        NOT('TEST_SCHEMA.ROW_REPRESENTATION_ITEM' IN TYPEOF(itet))
            )) = 0;
END_ENTITY;



--

ENTITY row_representation_item
    SUBTYPE OF (compound_representation_item);
    SELF\compound_representation_item.item_element : list_representation_item;
END_ENTITY;


ENTITY binary_representation_item
    SUBTYPE OF (representation_item);
    binary_value : BINARY;
END_ENTITY;

ENTITY point_and_vector
    SUBTYPE OF (compound_representation_item); --, geometric_representation_item);
    SELF\compound_representation_item.item_element : point_and_vector_members;
END_ENTITY;

TYPE point_and_vector_members = LIST [2:3] OF identifier;
END_TYPE;

TYPE label = STRING;
END_TYPE;

TYPE identifier = STRING;
END_TYPE;

END_SCHEMA;