columns partitioning row inserted in wrong partition

[martino merci]

Hello,
Let t be the following table:
CREATE TABLE t(
`a` tinyint(3) unsigned NOT NULL,
`b` tinyint(3) unsigned NOT NULL
) ENGINE=MyISAM
PARTITION BY RANGE COLUMNS(a,b)
(PARTITION p1 VALUES LESS THAN (54,54) ENGINE = MyISAM,
PARTITION p2 VALUES LESS THAN (54,106) ENGINE = MyISAM,
PARTITION p3 VALUES LESS THAN (54,164) ENGINE = MyISAM,
PARTITION p4 VALUES LESS THAN (54,204) ENGINE = MyISAM,
PARTITION p5 VALUES LESS THAN (54,MAXVALUE) ENGINE = MyISAM,
PARTITION p6 VALUES LESS THAN (106,54) ENGINE = MyISAM,
PARTITION p7 VALUES LESS THAN (164,54) ENGINE = MyISAM,
PARTITION p8 VALUES LESS THAN (204,54) ENGINE = MyISAM,
PARTITION p9 VALUES LESS THAN (MAXVALUE,54) ENGINE = MyISAM);

the row (1,1) is correctly inserted in p1.
Why the row (1,100) is inserted in p1 and not in p2, as I expected?
Thanks,
Martino