Mysql – Create foreign key doesn’t work, column types match

I'm trying to create a foreign key in mysql workbench, but keep getting this error:

I've checked the columns on both tables, and they match up as well as I can make them. One is CHAR(21) not null primary key, and the other is CHAR(21) not null.

Edit (again): (both tables)

First, the original table that I'm trying to link to:

    CREATE TABLE IF NOT EXISTS `db`.`Employee` (
      `employeeId` CHAR(21) NOT NULL,
      `departmentId` CHAR(21) NULL DEFAULT NULL,
      `chatStatusId` CHAR(21) NOT NULL DEFAULT 'd15a558946afbbd4a6046',
      `employeeNum` INT(4) NOT NULL,
      `payrollNum` INT(11) UNSIGNED NULL DEFAULT '0',
      `title` VARCHAR(50) NULL DEFAULT NULL,
      `dateHired` DATE NOT NULL,
      `terminationDate` DATE NULL DEFAULT NULL,
      `LastLogin` DATETIME NULL DEFAULT NULL,
      `rightMask` INT(11) NOT NULL COMMENT 'we should be using the right table instead',
      `teamId` INT(11) UNSIGNED NULL DEFAULT NULL COMMENT 'this is no longer really used',
      `IsTeamLead` TINYINT(4) NOT NULL DEFAULT '0',
      `bioId` INT(11) UNSIGNED NULL DEFAULT NULL,
      `emailSignature` TEXT NULL DEFAULT NULL,
      `notes` TEXT NULL DEFAULT NULL,
      PRIMARY KEY (`employeeId`),
      UNIQUE INDEX `employeeNum` (`employeeNum` ASC),
      INDEX `departmentId` (`departmentId` ASC),
      INDEX `chatStatusId` (`chatStatusId` ASC),
      INDEX `teamId` (`teamId` ASC),
      CONSTRAINT `Employee_ibfk_1`
        FOREIGN KEY (`employeeId`)
        REFERENCES `db`.`Person` (`personId`)
        ON DELETE CASCADE
        ON UPDATE CASCADE,
      CONSTRAINT `Employee_ibfk_10`
        FOREIGN KEY (`teamId`)
        REFERENCES `db`.`HaloTeam` (`teamId`)
        ON DELETE RESTRICT
        ON UPDATE RESTRICT,
      CONSTRAINT `Employee_ibfk_8`
        FOREIGN KEY (`departmentId`)
        REFERENCES `db`.`Department` (`departmentId`),
      CONSTRAINT `Employee_ibfk_9`
        FOREIGN KEY (`chatStatusId`)
        REFERENCES `db`.`ChatStatus` (`chatStatusId`)
        ON DELETE RESTRICT
        ON UPDATE RESTRICT)
ENGINE = InnoDB
DEFAULT CHARACTER SET = latin1
COLLATE = latin1_general_ci

And this is the new table I'm trying to create a foreign key on to the original table:

CREATE TABLE IF NOT EXISTS `db`.`ArticleNote` (
  `ArticleNoteID` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `ArticleID` INT(10) UNSIGNED NOT NULL,
  `Created` TIMESTAMP NOT NULL,
  `employeeId` CHAR(21) NOT NULL,
  `Note` VARCHAR(255) NOT NULL,
  PRIMARY KEY (`ArticleNoteID`),
  INDEX `fk_ANote_Article_idx` (`ArticleID` ASC),
  INDEX `fk_ANote_Employee_idx` (`employeeId` ASC),
  CONSTRAINT `fk_ANote_Article`
    FOREIGN KEY (`ArticleID`)
    REFERENCES `db`.`Article` (`ArticleID`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_ANote_Employee`
    FOREIGN KEY ()
    REFERENCES `db`.`Employee` ()
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB
DEFAULT CHARACTER SET = latin1
COLLATE = latin1_general_ci

And this is an example of a table that already has a foreign key (using the same column) as the one I'm trying to create in my new table:

CREATE TABLE IF NOT EXISTS `db`.`Article` (
  `ArticleID` INT(10) UNSIGNED NOT NULL AUTO_INCREMENT,
  `ArticleCategoryID` INT(10) UNSIGNED NOT NULL DEFAULT 1,
  `Url` VARCHAR(120) NOT NULL,
  `Title` VARCHAR(60) NOT NULL,
  `Summary` VARCHAR(255) NOT NULL,
  `Image` VARCHAR(200) NULL,
  `StatusIDE` INT(11) NOT NULL,
  `AreaIDE` INT(11) NULL,
  `CreatedAt` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
  `CreatedBy` CHAR(21) NULL DEFAULT NULL,
  `ExpiresAt` TIMESTAMP NULL DEFAULT NULL,
  `PayoutAmount` DECIMAL(11,2) NOT NULL DEFAULT 0.00,
  PRIMARY KEY (`ArticleID`),
  INDEX `fk_Aritcle_Category_idx` (`ArticleCategoryID` ASC),
  INDEX `fk_Article_Status_idx` (`StatusIDE` ASC),
  INDEX `fk_Article_Area_idx` (`AreaIDE` ASC),
  INDEX `fk_Article_Employee1_idx` (`CreatedBy` ASC),
  CONSTRAINT `fk_Article_Employee1`
    FOREIGN KEY (`CreatedBy`)
    REFERENCES `db`.`Employee` (`employeeId`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION,
  CONSTRAINT `fk_Article_ArtCat1`
    FOREIGN KEY (`ArticleCategoryID`)
    REFERENCES `db`.`ArticleCategory` (`ArticleCategoryID`)
    ON DELETE RESTRICT
    ON UPDATE CASCADE,
  CONSTRAINT `fk_Article_Status`
    FOREIGN KEY (`StatusIDE`)
    REFERENCES `db`.`DatabaseEnum` (`DatabaseEnumID`)
    ON DELETE RESTRICT
    ON UPDATE CASCADE,
  CONSTRAINT `fk_Article_Area`
    FOREIGN KEY (`AreaIDE`)
    REFERENCES `db`.`DatabaseEnum` (`DatabaseEnumID`)
    ON DELETE NO ACTION
    ON UPDATE NO ACTION)
ENGINE = InnoDB
DEFAULT CHARACTER SET = latin1
COLLATE = latin1_general_ci