sql error errno: 121

CREATE TABLE `users` (
`UID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
`username` VARCHAR(45) NOT NULL ,
`password` VARCHAR(100) NULL ,
`name` VARCHAR(100) NULL ,
`gender` BIT NULL ,
`email` VARCHAR(255) NULL ,
`phone` VARCHAR(30) NOT NULL ,
`verified` BIT NOT NULL DEFAULT 0 ,
`time_zone` INT NULL ,
`time_register` DATETIME NULL ,
`time_active` DATETIME NULL ,
PRIMARY KEY (`UID`) ,
UNIQUE INDEX `username_UNIQUE` (`username` ASC) ,
INDEX `verified_INDEX` (`verified` ASC) )
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8;




-- -----------------------------------------------------
-- Table `companies`
-- -----------------------------------------------------
CREATE TABLE `companies` (
`CID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
`name` VARCHAR(45) NOT NULL ,
`address` VARCHAR(100) NULL ,
`email` VARCHAR(255) NULL ,
`phone` VARCHAR(30) NULL ,
`link` TEXT NULL ,
`image_small` TEXT NULL ,
`image_large` TEXT NULL ,
`yahoo` VARCHAR(100) NULL ,
`linkin` VARCHAR(100) NULL ,
`twitter` VARCHAR(20) NULL ,
`description` TEXT NULL ,
`shoutout` VARCHAR(140) NULL ,
`verified` BIT NOT NULL DEFAULT 0 ,
PRIMARY KEY (`CID`) ,
INDEX `name_INDEX` (`name` ASC) ,
INDEX `verified_INDEX` (`verified` ASC) )
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8;


-- -----------------------------------------------------
-- Table `products`
-- -----------------------------------------------------
CREATE TABLE `products` (
`PID` INT UNSIGNED NOT NULL AUTO_INCREMENT ,
`CID` INT UNSIGNED NOT NULL ,
`name` VARCHAR(100) NULL ,
`description` TEXT NULL ,
`image_small` TEXT NULL ,
`image_large` TEXT NULL ,
`tag` VARCHAR(45) NULL ,
`price` DECIMAL(11,2) NULL ,
PRIMARY KEY (`PID`) ,
INDEX `tag_INDEX` (`tag` ASC) ,
INDEX `company.cid_FK` (`CID` ASC) ,
CONSTRAINT `company.cid_FK`
FOREIGN KEY (`CID` )
REFERENCES `companies` (`CID` )
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8;


-- -----------------------------------------------------
-- Table `users_companies`
-- -----------------------------------------------------
CREATE TABLE `users_companies` (
`UID` INT UNSIGNED NOT NULL ,
`CID` INT UNSIGNED NOT NULL ,
`role` INT UNSIGNED NULL ,
PRIMARY KEY (`CID`, `UID`) ,
INDEX `users.uid_FK` (`UID` ASC) ,
INDEX `company.cid_FK` (`CID` ASC) ,
CONSTRAINT `users.uid_FK`
FOREIGN KEY (`UID` )
REFERENCES `users` (`UID` )
ON DELETE NO ACTION
ON UPDATE NO ACTION,
CONSTRAINT `company.cid_FK`
FOREIGN KEY (`CID` )
REFERENCES `companies` (`CID` )
ON DELETE NO ACTION
ON UPDATE NO ACTION)
ENGINE = InnoDB
DEFAULT CHARACTER SET = utf8;

i got error

#1005 - Can't create table 'wew.users_companies' (errno: 121) (<a href="server_engines.php?engine=InnoDB&amp;page=Status&amp;token=3f35afdea97dd11f6b4ec1b669816738">Details...</a>)

can anyone tell me which one is the problem ?