Custom Validation Message Not Showing

Hi,

I’m trying to prevent duplicate email submission to my database using the filter below, which I added in Shortcodes, Actions, and Filters plugin, and CFDB plugin.

Everything works fine, i.e., once the email already exists in the database the user won’t be able to submit another form. The only problem is that when such an error occurred I still get the default validation error instead of the one I customized in the code below.

Any help? I really appreciate it!
thanks
/**
* @param $formName string
* @param $fieldName string
* @param $fieldValue string
* @return bool
*/
function is_already_submitted($formName, $fieldName, $fieldValue) {
require_once(ABSPATH . ‘wp-content/plugins/contact-form-7-to-database-extension/CFDBFormIterator.php’);
$exp = new CFDBFormIterator();
$atts = array();
$atts[‘show’] = $fieldName;
$atts[‘filter’] = “$fieldName=$fieldValue”;
$atts[‘unbuffered’] = ‘true’;
$exp->export($formName, $atts);
$found = false;
while ($row = $exp->nextRow()) {
$found = true;
}
return $found;
}

/**
* @param $result WPCF7_Validation
* @param $tag array
* @return WPCF7_Validation
*/
function my_validate_email($result, $tag) {
$formName = ‘MembershipClub’;
$fieldName = ‘m-email’;
$errorMessage = ‘A user with this email address is already registered’;
$name = $tag[‘name’];
if ($name == $fieldName) {
if (is_already_submitted($formName, $fieldName, $_POST[$name])) {
$result->invalidate($tag, $errorMessage);
}
}
return $result;
}

add_filter(‘wpcf7_validate_email*’, ‘my_validate_email’, 10, 2);