preg_match function doesn't work correctly in certain PHP script

Question

I am using preg_match function to filter unwanted characters from a textarea form in 2 PHP scripts I made, but in one of them seems not to work.

Here's the script with the problem:

<?php
    //Database connection, etc......

    mysql_select_db("etc", $con);
    $errmsg = '';
    $chido = $_POST['chido'];
    $gacho = $_POST['gacho'];
    $maestroid = $_POST['maestroid'];
    $comentario = $_POST['comment'];
    $voto = $_POST['voto'];

    if($_POST['enviado']==1) {
        if (preg_match ('/[^a-zA-Z áéíóúüñÁÉÍÓÚÜÑ]/i', $comentario))
            $errmsg = 1;
        if($errmsg == '') {
            //here's some queries, etc
        }
    }

    if($errmsg == 1)
        echo "ERROR: You inserted invalid characters...";
?>

So as you can see the preg_match just filter unwanted chracters like !"#$%&/() etc..

But every time I type a special character like 'ñ' or 'á' it triggers the error code.

I have this very similar script that works perfectly with the same preg_match and filters just the unwanted characters:

//Database connection, etc..
mysql_select_db("etc", $con);
$errmsg = '';

if ($_POST['enviado']==1) {
     $nombre = $_POST['nombre'];
     $apodo = $_POST['apodo'];
     $mat1 = $_POST['mat1'];
     $mat2 = $_POST['mat2'];
     $mat3 = $_POST['mat3'];

     if (preg_match ('/[^a-zA-Z áéíóúüñÁÉÍÓÚÜÑ]/i', $nombre))
         $errmsg = 1;


     if($errmsg == '') {
         //more queries after validation
     }
}

if($errmsg == 1)
    echo "ERROR: etc......."
?>

So the question is, what am I doing wrong in the first script??

I tried everything but always fails and shows the error.

Any suggestion?

Answer 1

This might help: http://www.phpwact.org/php/i18n/charsets