รบกวนช่วยทีนะค่ะ CKEDITOR รับค่า textarea ผ่าน ID เห็นค่าว่าง

<script type="text/javascript">
	$(document).ready(function(){			
		autosave();
	});
	
	function autosave()
	{
		var t = setTimeout("autosave()", 20);
		
		var ckeditor = $("#ckeditor").val();		
		var title = $("#title").val();
		var category = $("#category").val();
		var sub_category = $("#sub_category").val();
		var status = $("#status").val();
		var tag1 = $("#tag1").val();
		var tag2 = $("#tag2").val();
		var tag3 = $("#tag3").val();
		var tag4 = $("#tag4").val();
		var tag5 = $("#tag5").val();

			
		if (title.length > 0 || content.length > 0)
		{
			$.ajax(
			{
				type: "POST",
				url: "autosave.php",
				data: "id="   <?php echo $id ?>   "&title="   title   "&category="   category   "&sub_category="   sub_category   "&ckeditor="   ckeditor   "&status="   status   "&tag1="   tag1   "&tag2="   tag2   "&tag3="   tag3   "&tag4="   tag4   "&tag5="   tag5,
				cache: false,
				success: function(message)
				{	
					$("#timestamp").empty().append(message);
				}
			});
		}
	} 
	</script>	

<textarea rows="" cols="" class="ckeditor" name="ckeditor" id="ckeditor"></textarea>

<?php
//include DB configuration file
include('connectdb.php');

$id = $_REQUEST[id];
$title = $_POST[title];
$category =$_POST[category];
$sub_category =$_POST[sub_category];
$status = $_POST[status];
$ckeditor = $_POST[ckeditor];
$tag1 = $_POST[tag1];
$tag2 =$_POST[tag2];
$tag3 =$_POST[tag3];
$tag4 = $_POST[tag4];
$tag5 = $_POST[tag5];
$date_art=date("y-m-d");

//save contents to database
$sql= "UPDATE article SET  title = '$title', category = '$category', sub_category = '$sub_category', status = '$status', detail = '$ckeditor', tag1 = '$tag1', tag2 = '$tag2', tag3 = '$tag3', tag4 = '$tag4', tag5 = '$tag5' ,date_art = '$date_art' WHERE id = '$id'";
$result = mysql_query($sql);

//get timestamp
$result = mysql_query("SELECT timestamp FROM article WHERE id = '$id'");
$timestamp = mysql_result($result, 0);

//output timestamp
echo 'Auto Saved: ', $timestamp, $editor1, $ckeditor;
?>