Problem With Search Operators

[Tru Call]

Schema:
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
DROP TABLE IF EXISTS articles;
CREATE TABLE articles (
id INT UNSIGNED AUTO_INCREMENT NOT NULL PRIMARY KEY,
title VARCHAR(200),body TEXT,
FULLTEXT (title,body)
);

INSERT INTO articles (title,body) VALUES
('Titolo di prova','descrizione articolo'),
('In diretta dall\'olimpico','Andrà in onda...');
-- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --

Query 1: SELECT * FROM articles WHERE MATCH (title,body) AGAINST ('*dirett*' IN BOOLEAN MODE);
RS = 1 record

Query 2: SELECT * FROM articles WHERE MATCH (title,body) AGAINST ('*olimp*' IN BOOLEAN MODE);
RS = 0 record

The second query return is empty, I don't understand why.

Any hints?

MySQL Version: 5.0.18


Thanks in advance.