onSignChange help

I have made a little test plugin for myself with the onSignChange, but when i place a sign (wall sign)
and typing [WHO] it give you your ip and display name, and its working,
but when i type like "Hello" its still pops up, this is the code

Code:

    public void onSignChange(SignChangeEvent event) {
        Player player = event.getPlayer();
        if (event.getBlock().getType() == Material.WALL_SIGN)

        {
            if (event.getLine(0).equalsIgnoreCase("[WHO]") && config.getString("who_enabled_sign").equals("true"));

            {
                player.sendMessage(ChatColor.DARK_BLUE + "Your IP Is:"    + ChatColor.DARK_RED + player.getAddress());
                player.sendMessage(ChatColor.DARK_GREEN + "Your Display Name is:" + ChatColor.RED + player.getDisplayName());
            }
        }
 
        }

Please help