Table partitioning -> primary key error

Hi,

While creating partition on a table , the following error occured. How to resolve it?

A PRIMARY KEY must include all columns in the table's partitioning function

CREATE TABLE article_part (

article_id int(11) NOT NULL AUTO_INCREMENT,

article_title text,

source_edition_id bigint(15) DEFAULT NULL,

paper_page_no int(10) DEFAULT NULL,

co_ordinates varchar(500) DEFAULT NULL,

image_url varchar(2000) DEFAULT NULL,

user_id bigint(15) DEFAULT NULL,

category_id bigint(15) DEFAULT NULL,

author varchar(150) DEFAULT NULL,

article_inserted_time datetime DEFAULT NULL,

feedback varchar(20) DEFAULT NULL,

editions_downloaded_id bigint(15) DEFAULT NULL,

description text,

is_deleted enum('Y','N') DEFAULT NULL,

reason_article bigint(15) DEFAULT NULL,

article_truth bigint(15) DEFAULT NULL,

parent_article_id bigint(15) DEFAULT NULL,

is_linked enum('Y','N') DEFAULT 'N',

is_grouped enum('Y','N') DEFAULT 'N',

is_important enum('Y','N') DEFAULT 'N',

involved varchar(10) DEFAULT NULL,

is_uploaded enum('Y','N') DEFAULT 'N',

source_url varchar(500) DEFAULT NULL,

from_source varchar(500) DEFAULT NULL,

actionable enum('Y','N') DEFAULT 'N',

news_bulletin enum('Y','N') DEFAULT 'N',

news_organization int(11) DEFAULT NULL,

article_size bigint(15) DEFAULT NULL,

article_perc float DEFAULT '0',

article_created_time datetime DEFAULT NULL,

is_old_article enum('Y','N') DEFAULT 'N',

is_counter_attack enum('Y','N') DEFAULT 'N',

counter_attack_news_organization int(11) DEFAULT NULL, PRIMARY KEY (article_id))

ENGINE=InnoDB AUTO_INCREMENT=286802795 DEFAULT CHARSET=utf8

PARTITION BY RANGE( TO_DAYS(article_inserted_time) ) (

PARTITION p20110401 VALUES LESS THAN (TO_DAYS('2011-04-02')),

PARTITION p20110402 VALUES LESS THAN (TO_DAYS('2011-04-03')),

PARTITION p20110403 VALUES LESS THAN (TO_DAYS('2011-04-04')),

PARTITION p20110404 VALUES LESS THAN (TO_DAYS('2011-04-05')),

PARTITION p20110426 VALUES LESS THAN (TO_DAYS('2011-04-27')),

PARTITION p20110427 VALUES LESS THAN (TO_DAYS('2011-04-28')),

PARTITION p20110428 VALUES LESS THAN (TO_DAYS('2011-04-29')),

PARTITION p20110429 VALUES LESS THAN (TO_DAYS('2011-04-30')),

PARTITION future VALUES LESS THAN MAXVALUE