Error 150, I can't find the mistake. [SOLVED] (2 replies)

Hi, I'm trying to make a table with foreign keys but when I load the sql script it fails in the last foreign key. If I delete it works but the referenced value name is correct...

I'm really lost because I never had this problem and surely it's a stupid mistake but I can't find it

Thx in advance.

Here the sql script:

CREATE TABLE `Alumno` (
`DNI` VARCHAR(9) NOT NULL,
`nombre` VARCHAR(15),
`apellido1` VARCHAR(15),
`direccion` VARCHAR(70),
`fechaNacimiento` DATE,
PRIMARY KEY (`DNI`)
) ENGINE=InnoDB;

CREATE TABLE `Seccion` (
`codigoAuto` VARCHAR(5) NOT NULL,
`digitoSeccion` VARCHAR(5) NOT NULL,
`direccion` VARCHAR(70),
`telefono` VARCHAR(70),
`horario` VARCHAR(20),
PRIMARY KEY (`codigoAuto`,`digitoSeccion`)
) ENGINE=InnoDB;

CREATE TABLE `ContratoAprendizaje` (
`matricula` VARCHAR(10) NOT NULL,
`fechaFirma` DATE,
`duracion` VARCHAR(5),
`condiciones` VARCHAR(140),
`observaciones` VARCHAR(140),
`alumno` VARCHAR(9) NOT NULL,
`autoescuela` VARCHAR(5) NOT NULL,
`seccion` VARCHAR(5) NOT NULL,
PRIMARY KEY (`matricula`,`alumno`,`autoescuela`,`seccion`),
FOREIGN KEY (`alumno`) REFERENCES `Alumno`(`DNI`) ON DELETE RESTRICT ON UPDATE RESTRICT,
FOREIGN KEY (`autoescuela`) REFERENCES `Seccion`(`codigoAuto`) ON DELETE RESTRICT ON UPDATE RESTRICT,
FOREIGN KEY (`seccion`) REFERENCES `Seccion`(`digitoSeccion`) ON DELETE RESTRICT ON UPDATE RESTRICT
) ENGINE=InnoDB;