How to add a new Validation

Hi,

I am using the brute-fore and changed the login page url. But when i add the new feild in the login page using the functions.php in my theme for validation it doesnt work. This is not effective using the brute force. But when i use the http://www.mywebsite.com/wp-login.php it works fine.

The code i wrote for adding additional feild and validation in my login is given below

add_action('login_form','my_added_login_field');
function my_added_login_field(){
    //Output your HTML
?>
    <p>
        <label for="partner">Partner</label><br>
        <?php
		global $wpdb;
			$result=$wpdb->get_results( "SELECT * FROM hp3ic1e_partners");
			?>

		<select name="partnersname" id="partnership">
		<?php
		foreach($result as $row)
		{?>
			<option value="<?php echo $row->partnername;?>"><?php echo $row->partnername;?></option>
		<?php
		}
		?>
			</select>
    </p>
<?php
}
add_filter( 'authenticate', 'my_custom_authenticate', 10, 3 );
function my_custom_authenticate( $user, $username, $password ){
    //Get POSTED value

    $my_value = $_POST['partnersname'];
	//Get user object
    $user = get_user_by('login', $username );

    //Get stored value
        $stored_value = get_user_meta($user->ID, 'user_partnership', true);

    if(!$user || empty($my_value) || $my_value !=$stored_value){
        //User note found, or no value entered or doesn't match stored value - don't proceed.
            remove_action('authenticate', 'wp_authenticate_username_password', 20); 

        //Create an error to return to user
            $user = new WP_Error( 'denied', __("<strong>ERROR</strong>: You're unique identifier was invalid.") );
    }

    //Make sure you return null
    return null;
}

https://wordpress.org/plugins/all-in-one-wp-security-and-firewall/