Probleme php elseif non resolu

Bonjour a tous,

j ai ce formulaire d'inscription je passe par des elseif pour mettre en condition le remplissage des champs mais j ai des paramètres qui se je les mets hors des elseif j ai un message d'erreur [QUOTE]syntax error unexpected T_ELSEIF[/QUOTE] et si j insere ces paramètres dans mes accolades elseif bah il ne marche plus...

ces paramètres sont en gras dans le code ci dessous

code avec paramètre dans les elseif:

[CODE]if (isset($_POST['submit'])) {

if (!$_POST['nom'] | !$_POST['prenom'] | !$_POST['mail'] | !$_POST['username'] | !$_POST['pass'] | !$_POST['pass2'] ) {
echo "<script language=\"JavaScript\">\n";
echo "alert('Champs requis non remplis');";
echo 'window.history.back();';
echo "</script>";
}

elseif (!get_magic_quotes_gpc()) {
[B]$usercheck = $_POST['username'];
$check = mysql_query("SELECT username FROM users WHERE username = '$usercheck'")
or die(mysql_error());
$check2 = mysql_num_rows($check);[/B]
$_POST['username'] = addslashes($_POST['username']);
}

//if the name exists it gives an error
elseif ($check2 != 0) {
echo "<script language=\"JavaScript\">\n";
echo "alert('Utilisateur déjà utilisé');";
echo 'window.history.back();';
echo "</script>";
}

// this makes sure both passwords entered match
elseif ($_POST['pass'] != $_POST['pass2']) {
echo "<script language=\"JavaScript\">\n";
echo "alert('Ls mots de passe ne correspondent pas');";
echo 'window.history.back();';
echo "</script>";
}

elseif (!get_magic_quotes_gpc()) {
[B]$_POST['pass'] = md5($_POST['pass']);[/B]
$_POST['pass'] = addslashes($_POST['pass']);
$_POST['username'] = addslashes($_POST['username']);
}
else {

$email = $_POST['mail'];
$verif="!^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]{2,}\.[a-zA-Z]{2,4}$!"; //pour analysé l'email
if(preg_match($verif,$email)){
$insert = "INSERT INTO users (nom, prenom, telephone, mail, adresse, cp, ville, username, password)
VALUES ('".$_POST['nom']."', '".$_POST['prenom']."', '".$_POST['telephone']."', '".$_POST['mail']."', '".$_POST['adresse']."', '".$_POST['cp']."', '".$_POST['ville']."', '".$_POST['username']."', '".$_POST['pass']."' )";
$add_member = mysql_query($insert);

echo "<script language=\"JavaScript\">\n";
echo "window.location.href = 'index.php'";
echo "</script>";
}
else
{
echo "<script language=\"JavaScript\">\n";
echo "alert('Email non valide');";
echo 'window.history.back();';
echo "</script>";
}
}
}[/CODE]

code 2 avec paramètre hors elseif :

[CODE]if (isset($_POST['submit'])) {

if (!$_POST['nom'] | !$_POST['prenom'] | !$_POST['mail'] | !$_POST['username'] | !$_POST['pass'] | !$_POST['pass2'] ) {
echo "<script language=\"JavaScript\">\n";
echo "alert('Champs requis non remplis');";
echo 'window.history.back();';
echo "</script>";
}

elseif (!get_magic_quotes_gpc()) {
$_POST['username'] = addslashes($_POST['username']);
}
[B]$usercheck = $_POST['username'];
$check = mysql_query("SELECT username FROM users WHERE username = '$usercheck'")
or die(mysql_error());
$check2 = mysql_num_rows($check);[/B]

elseif ($check2 != 0) {
echo "<script language=\"JavaScript\">\n";
echo "alert('Utilisateur déjà utilisé');";
echo 'window.history.back();';
echo "</script>";
}

elseif ($_POST['pass'] != $_POST['pass2']) {
echo "<script language=\"JavaScript\">\n";
echo "alert('Ls mots de passe ne correspondent pas');";
echo 'window.history.back();';
echo "</script>";
}

[B]$_POST['pass'] = md5($_POST['pass']);[/B]
elseif (!get_magic_quotes_gpc()) {
$_POST['pass'] = addslashes($_POST['pass']);
$_POST['username'] = addslashes($_POST['username']);
}
else {

$email = $_POST['mail'];
$verif="!^[a-zA-Z0-9._-]+@[a-zA-Z0-9._-]{2,}\.[a-zA-Z]{2,4}$!"; //pour analysé l'email
if(preg_match($verif,$email)){
$insert = "INSERT INTO users (nom, prenom, telephone, mail, adresse, cp, ville, username, password)
VALUES ('".$_POST['nom']."', '".$_POST['prenom']."', '".$_POST['telephone']."', '".$_POST['mail']."', '".$_POST['adresse']."', '".$_POST['cp']."', '".$_POST['ville']."', '".$_POST['username']."', '".$_POST['pass']."' )";
$add_member = mysql_query($insert);

echo "<script language=\"JavaScript\">\n";
echo "window.location.href = 'index.php'";
echo "</script>";
}
else
{
echo "<script language=\"JavaScript\">\n";
echo "alert('Email non valide');";
echo 'window.history.back();';
echo "</script>";
}
}
}[/CODE]