ROWS function available inside subquery

Question

Can somebody explain why I'm not able to use the ROWS function inside a subquery?

I'm able to use the ROWS function with a standard SELECT statement but when using it inside a subquery, I get this error:

Invalid token.

Dynamic SQL Error.
SQL error code = -104.
Token unknown - line 3, char 26.

This SQL is not working:

SELECT 
    (SELECT rel.NAME 
     FROM RELATIONS rel ROWS 1 /*<--*/
    ) AS rel1,
    PR.CODE,
    PR.OMS,
    ADM.ADMOMS
FROM 
    PROJECTS pr
JOIN
    ADMINISTRATIONS adm ON ADM.ID = PR.ADM_ID
WHERE 
    pr.STATUS < '008' AND
    pr.CODE = "1234"

However, this SQL IS working:

SELECT r.NAME 
FROM RELATIONS r ROWS 1 /*<--*/