Most of the time, if a network orders a pilot to series, that show is given a chance to prove itself, even if it only gets a summer burn-off run. Every so often, however, a network orders a pilot to series then seems to immediately lose faith in it, often for no apparent reason, leaving several episodes produced, never to be seen by audiences.
via The unseen: 24 TV shows produced but never properly aired | TV | Inventory | The A.V. Club.