php - syntax error, unexpected T_IS_EQUAL

 

            if(isset($_POST['zapisz'])) { 
 $zapytanie_update = mysql_query("UPDATE
            `emotki` SET `kod` = '".$_POST['kod']."',`opis` = '".$_POST['opis']."', `glowna` =
            '".$_POST['glowna']."' WHERE id= $id");
 echo 'Emotka
            zapisana.
« Powrót';

            }

 $usun = $_POST['usun'];
 if(isset($usun ==
            1)
 {
 $usuwaj = mysql_query("DELETE FROM `emotki` WHERE 'id'=
            $id");
 }




else
            {
?>

i
have
( ! ) Parse error: syntax error, unexpected T_IS_EQUAL, expecting ',' or
')' in C:\wamp\www\emotki_admin\edytuj.php on line
63

line 63 is
if(isset($usun ==
1)

where is
error?