error 1503: A primary key must include all columns in the table

[Aamir Sohail]

hii,

I have a table structure like-
CREATE TABLE `cdr` (
`id` bigint(20) NOT NULL AUTO_INCREMENT,
`dataPacketDownLink` bigint(20) DEFAULT NULL,
`dataPacketUpLink` bigint(20) DEFAULT NULL,
`dataPlanEndTime` datetime DEFAULT NULL,
`dataPlanStartTime` datetime DEFAULT NULL,
`dataVolumeDownLink` bigint(20) DEFAULT NULL,
`dataVolumeUpLink` bigint(20) DEFAULT NULL,
`dataplan` varchar(255) DEFAULT NULL,
`dataplanType` varchar(255) DEFAULT NULL,
`createdOn` datetime DEFAULT NULL,
`deviceName` varchar(500) DEFAULT NULL,
`duration` int(11) NOT NULL,
`effectiveDuration` int(11) NOT NULL,
`hour` int(11) DEFAULT NULL,
`eventDate` datetime DEFAULT NULL,
`msisdn` bigint(20) DEFAULT NULL,
`quarter` int(11) DEFAULT NULL,
`validDays` int(11) DEFAULT NULL,
`dataLeft` bigint(20) DEFAULT NULL,
`completedOn` datetime DEFAULT NULL,
PRIMARY KEY (`id`),
KEY `msisdn_index` (`msisdn`),
KEY `eventdate_index` (`eventDate`)
) ENGINE=MyISAM AUTO_INCREMENT=55925171 DEFAULT CHARSET=latin1

and when i am creating partition -
ALTER TABLE cdr PARTITION BY RANGE (TO_DAYS(eventdate))
(
PARTITION p01 VALUES LESS THAN (TO_DAYS(’2013-09-01′)),
PARTITION p02 VALUES LESS THAN (TO_DAYS(’2013-09-15′)),
PARTITION p03 VALUES LESS THAN (TO_DAYS(’2013-09-30′)),
PARTITION p04 VALUES LESS THAN (MAXVALUE));

getting the error 1503: A primary key must include all columns in the table :( i have read everywhere about this but not getting anything so please let me know how to partition this table. i have 20+ million records in it.
Thank you.