Thesql error creating table

I was creating a DB with mySQL, and this error appeared:

Can't create table 'projectefinal.apuntats' (errno: 150)

I've got this:

    CREATE DATABASE IF NOT EXISTS projectefinal

CREATE TABLE IF NOT EXISTS usuaris(
    id INT NOT NULL AUTO_INCREMENT,
    nom TEXT NOT NULL,
    cognoms TEXT NOT NULL,
    dni VARCHAR(9) NOT NULL,
    aturat BOOLEAN NOT NULL,
    PRIMARY KEY(id),
    UNIQUE(dni)
);

CREATE TABLE IF NOT EXISTS cursos(
    id INT NOT NULL AUTO_INCREMENT,
    nom TEXT NOT NULL,
    maximspersones INT NOT NULL,
    PRIMARY KEY(id)
);

CREATE TABLE IF NOT EXISTS apuntats(
    id INT NOT NULL AUTO_INCREMENT,
    idcurs INT NOT NULL,
    idusuari INT NOT NULL,
    coneixements TEXT,
    motiu TEXT,
    FOREIGN KEY(idcurs)
        REFERENCES id(curs)
        ON DELETE CASCADE,
    FOREIGN KEY(idusuari)
        REFERENCES id(usuaris)
        ON DELETE CASCADE,
    PRIMARY KEY(id)
);

I've read before that may happends because a table is not created, but it is, I went one by one ("usuaris" first, "curs" for the second, and finally "apuntats") and it gave me that error. Any help on how to fix it?

Thanks again, as always!