error 121

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Tengo un scrip sql y cuando lo ejecuto no me crea la tabla stores y me da este error:

el error lo da al intentar crear la tabla stores, la tabla users la crea sin problemas, solo la pongo para que vean la relación

Código:

ERROR: Error 1005: Can't create table 'tientas.stores' (errno: 121)

Aqui la consulta de creacion de las tablas users y stores:

Esta es de users:

Código:

-- Table `tientas`.`users`

-- -----------------------------------------------------

CREATE  TABLE IF NOT EXISTS `tientas`.`users` (

  `id` INT NOT NULL AUTO_INCREMENT ,

  `username` VARCHAR(45) NOT NULL ,

  `password` VARCHAR(45) NOT NULL ,

  `phone` VARCHAR(45) NOT NULL ,

  `email` VARCHAR(45) NOT NULL ,

  `address` VARCHAR(150) NOT NULL ,

  `picture` VARCHAR(200) NULL ,

  `active` TINYINT(1)  NOT NULL ,

  `group_id` INT NOT NULL ,

  `regione_id` INT NOT NULL ,

  `created` DATETIME NOT NULL ,

  `modified` DATETIME NOT NULL ,

  PRIMARY KEY (`id`) ,

  INDEX `group_id` (`group_id` ASC) ,

  INDEX `regione_id` (`regione_id` ASC) ,

  CONSTRAINT `group_id`

    FOREIGN KEY (`group_id` )

    REFERENCES `tientas`.`groups` (`id` )

    ON DELETE NO ACTION

    ON UPDATE NO ACTION,

  CONSTRAINT `regione_id`

    FOREIGN KEY (`regione_id` )

    REFERENCES `tientas`.`regiones` (`id` )

    ON DELETE NO ACTION

    ON UPDATE NO ACTION)

ENGINE = InnoDB

DEFAULT CHARACTER SET = utf8

COLLATE = utf8_spanish_ci;

Y esta es la de stores:

Código:

-- -----------------------------------------------------

-- Table `tientas`.`stores`

-- -----------------------------------------------------

CREATE  TABLE IF NOT EXISTS `tientas`.`stores` (

  `id` INT NOT NULL AUTO_INCREMENT ,

  `user_id` INT NOT NULL ,

  `name` VARCHAR(45) NOT NULL ,

  `category` VARCHAR(45) NOT NULL ,

  `category_id` INT NOT NULL ,

  `created` DATETIME NOT NULL ,

  `modified` DATETIME NOT NULL ,

  PRIMARY KEY (`id`) ,

  INDEX `user_id` (`user_id` ASC) ,

  INDEX `category_id` (`category_id` ASC) ,

  CONSTRAINT `user_id`

    FOREIGN KEY (`user_id` )

    REFERENCES `tientas`.`users` (`id` )

    ON DELETE CASCADE

    ON UPDATE NO ACTION,

  CONSTRAINT `category_id`

    FOREIGN KEY (`category_id` )

    REFERENCES `tientas`.`categorys` (`id` )

    ON DELETE NO ACTION

    ON UPDATE NO ACTION)

ENGINE = InnoDB

DEFAULT CHARACTER SET = utf8

COLLATE = utf8_spanish_ci;

Que podra ser?