MySQL - #1215 - No puede adicionar clave extranjera constraint

SET FOREIGN_KEY_CHECKS = 0;

CREATE TABLE `mw_zone` (

`zone_id` int(11) NOT NULL,

`country_id` int(11) NOT NULL,

`name` varchar(150) NOT NULL,

`code` varchar(50) NOT NULL,

`status` char(10) NOT NULL DEFAULT 'active',

`date_added` datetime NOT NULL,

`last_updated` datetime NOT NULL

) ENGINE=InnoDB DEFAULT CHARSET=utf8;

ALTER TABLE `mw_zone`

ADD PRIMARY KEY (`zone_id`),

ADD KEY `fk_zone_country1_idx` (`country_id`);

ALTER TABLE `mw_zone`

MODIFY `zone_id` int(11) NOT NULL AUTO_INCREMENT, AUTO_INCREMENT=3970;

ALTER TABLE `mw_zone`

ADD CONSTRAINT `fk_zone_country1` FOREIGN KEY (`country_id`) REFERENCES `mw_country` (`country_id`) ON DELETE CASCADE ON UPDATE NO ACTION;

CREATE TABLE USUARIO (

	IDDOCUMENTO INT UNSIGNED AUTO_INCREMENT  NOT NULL ,

	DOCUMENTO INT(15) NOT NULL,

	IDTDOCUMENTO_FK INT NOT NULL,

	INDEX (IDTDOCUMENTO_FK),

	FOREIGN KEY(IDTDOCUMENTO_FK) REFERENCES TIPO_DOCUMENTO (IDTDOCUMENTO),

	NOMBREUNO VARCHAR(20) NOT NULL,

	NOMBREDOS VARCHAR(20) NOT NULL,

	APELLIDOUNO VARCHAR(20) NOT NULL,

	APELLIDODOS VARCHAR(20) NOT NULL,

	DIRECCION VARCHAR(20) NOT NULL,

	CORREO VARCHAR(20) NOT NULL,

	FACTUAL TIMESTAMP DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP NOT NULL,

	CONSTRAINT IDDOCUMENTO PRIMARY KEY (IDDOCUMENTO)

)ENGINE = InnoDB

COLLATE = utf8_spanish_ci;