Can't mix (latin1_swedish_ci,NUMERIC) and (utf8_unicode_ci,IMPLICIT) for MATCH

CREATE TABLE `sitelog` (

  `id` int(10) unsigned NOT NULL AUTO_INCREMENT,

  `added` datetime NOT NULL,

  `txt` text COLLATE utf8_unicode_ci NOT NULL,

  `uid` int(11) NOT NULL,

  `id2` int(11) NOT NULL,

  `id2_type` char(1) COLLATE utf8_unicode_ci NOT NULL,

  PRIMARY KEY (`id`),

  KEY `uid` (`uid`),

  KEY `id2` (`id2`)

) ENGINE=MyISAM DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;

select txt, unix_timestamp(added), uid, id2, id2_type    from sitelog    where match (id2, uid, txt) against ('' in boolean mode); 

ERROR 1270 (HY000): Illegal mix of collations (latin1_swedish_ci,NUMERIC), (latin1_swedish_ci,NUMERIC), (utf8_unicode_ci,IMPLICIT) for operation 'match'