Ajaxla veri çekemiyorum

$(document).ready(function(){
    $(".user-area-content").click(function(){
        $(".user-menu").toggle();
    });


    



    $(window).scroll(function(){
        var lastID = $('.load-more').attr('lastID');
        if ($(window).scrollTop() == $(document).height() - $(window).height() && lastID != 0){
            $.ajax({
                type:'POST',
                url:'ajax.php',
                data:'id='+lastID,
                beforeSend:function(html){
                    $('.load-more').show();
                },
                success:function(html){
                    $('.load-more').remove();
                    $('#user-content').append(html);
                }
            });
        }
    });


});

<div class="load-more" lastID="<?php echo $postID; ?>" style="display: none;">
                <img src="loading.gif"/>
            </div>

echo $lastID = $_POST['id'];