You have to enable foreign keys support:

    PRAGMA foreign_keys=ON;

Reference: http://www.sqlite.org/foreignkeys.html

Example:

    sqlite> create table A(
       ...>     id integer primary key autoincrement,
       ...>     subject text not null
       ...> );
    sqlite> 
    sqlite> create table B(
       ...>     id integer primary key autoincrement,
       ...>     text integer references A(id)
       ...>         on delete restrict
       ...>         deferrable initially deferred
       ...>         unique
       ...> );
    sqlite> insert into a values(1,1),(2,2);
    sqlite> insert into b(text) values(3);
    sqlite> pragma foreign_keys=on;
    sqlite> insert into b(text) values(4);
    Error: foreign key constraint failed
    sqlite>