Custom validation Contact Form 7

i would like to validate a text tag in contact form 7, to validate an italian car plate, this is my RegExp in JavaScript:

<script>
function targaCheck(){
var targaRExp = /^(([a-zA-Z]{2}\d{3}[a-zA-Z]{2})|(([a-zA-Z]{2}|roma)(\d{5}|\d{6})))$/i;
var targa = document.getElementById(“targa”).value;
if( targaRExp.test(targa) ) {
alert(“Correct”);
}else {
alert(“Incorrect”);
}
}
</script>

To validate the contact form 7 i have to use “add_filter” in function.php of my WP site, but when i insert my code it doesn’t work. This is my code into function.php

    //add filter for text field validation
include("cf7-custom-validation.php");
add_filter('wpcf7_validate_text*', 'cf7_custom_form_validation', 10, 2); // Req. text field

// TARGA ITALIANA

    if($name == 'targa') {
        $targa = $_POST['targa'];

        if($targa != '') {
                if(!preg_match('/^(([a-zA-Z]{2}\d{3}[a-zA-Z]{2})|(([a-zA-Z]{2}|roma)(\d{5}|\d{6})))$/i', $targa)) {
                $result['valid'] = false;
                $result['reason'][$name] = 'La Targa inserita non è valida';
            }
        }
    }

Where am I wrong?

Please help me

Thanks!