MySQL ERROR 1215 (HY000): cannot add foreign key constraint

I searched everywhere about this error and saw many examples, and yet I cannot understand what happened to my script. I am sorry if this is a common problem, but searching on it has not helped me so far. Here is the script:

CREATE DATABASE IF NOT EXISTS ventas;
USE ventas

CREATE TABLE TIENDAS (
nif varchar(10) not null,
nombre varchar(20),
direccion varchar(20),
poblacion varchar(20),
provincia varchar(20) check (provincia = upper(provincia)),
codpostal int(5),
PRIMARY KEY (nif)
) ENGINE=INNODB;

CREATE TABLE FABRICANTES (
cod_fabricante int(3) not null,
nombre varchar(15) check (nombre = upper(nombre)),
pais varchar(15) check (pais = upper(pais)),
PRIMARY KEY (cod_fabricante)
) ENGINE=INNODB;

CREATE TABLE ARTICULOS (
articulo varchar(20) not null,
cod_fabricante int(3) not null,
peso int(3) unsigned not null CHECK (peso > 0),
categoria varchar(10) not null,
precio_venta int(4) unsigned CHECK (precio_venta > 0),
precio_costo int(4) unsigned CHECK (precio_costo > 0),
existencias int(5),
PRIMARY KEY (articulo,cod_fabricante,peso,categoria),
FOREIGN KEY (cod_fabricante) references FABRICANTES (cod_fabricante)
) ENGINE=INNODB;

CREATE TABLE PEDIDOS (
nif varchar(10) not null,
articulo varchar(20) not null,
cod_fabricante int(3) not null,
peso int(3) unsigned not null CHECK (peso > 0),
categoria varchar(10) not null,
fecha_pedido date not null,
unidades_pedidas int(4),
PRIMARY KEY (nif,articulo,cod_fabricante,peso,categoria,fecha_pedido),
FOREIGN KEY (cod_fabricante) references FABRICANTES (cod_fabricante),
FOREIGN KEY (articulo) references ARTICULOS (articulo) ON DELETE CASCADE,
FOREIGN KEY (cod_fabricante) references ARTICULOS (cod_fabricante) ON DELETE CASCADE,
FOREIGN KEY (peso) references ARTICULOS (peso) ON DELETE CASCADE,
FOREIGN KEY (categoria) references ARTICULOS (categoria) ON DELETE CASCADE,
FOREIGN KEY (nif) references TIENDAS (nif)
) ENGINE=INNODB;

Many thanks for your help.