Ok, But I suspect that Firebird doesn't like the join (select..) statment.
see my Firebird SQL:
Select A.ARTI_CODI, A.alvl_unidades,A.alvl_precio, A.Alvc_fecha_alta
from dib_consum_last_articles_2(20013) A INNER JOIN (
Select ARTI_CODI, MAX(ALVC_FECHA_ALTA) LastDate FROM ALVC
JOIN ALVL on...