Input in array

Am un input in care utilizatorul poate introduce o cifra, si un array cu 5 cifre. Vreau sa imi faca o verificarea care valoarea introdusa in input se afla in array sa-mi afiseze un text si else alt text.. Am incercat ceva insa nu stiu cat de corest este..

Cod PHP:

---

                        <form method="POST" action="">
                        <input class="verif" type="text" name="verificare"><input type="submit" value="Verifica!"><br/>
                        </form>
                        <?php
                         $nr = $_POST['verificare'];
                         if ($_SERVER['REQUEST_METHOD'] == 'POST')
                         {
                            $sir = array("1", "2", "3" , "4" , "5" , "6" , "7" , "8" , "9");
                            if (array_key_exists('$nr', $sir)) {
                              echo "Numarul este corect!";
                            }
                            else 
                            {
                                echo "Numarul este incorect!";
                            }
                        }    
                        ?>

---

Cum pot verifica daca valoarea din input, anume variabila $nr apartine acelui array ?

in_array()

PHP: in_array - Manual

Am incercat cu in_array insa tot nu vrea.. imi apare ELSE`ul..

if (in_array($nr, $sir))

Fara glilimele la $nr.