How to remain bottom the scroll bar using javascript/jquery?

[Exequiel]

My problem here is that the scroll bar is not staying in bottom, after loading the data using ajax the scroll bar still on top. but when i place the code for positioning the scroll bar at the bottom before doing the function see_message_tor eply(deskid); it works, but after doing this function its not working. . can any body help me my problem?:)

function save_reply(theuser, deskid)
{
	var reply = $("textarea[name=reply_fields]").val();
	
	if(reply!="")
	{
		//when i put it here it works!
		
		if(reply.length >= 10)
		{
			
			$.ajax({
				type:'post',
				url:URL+"index.php/company/save_reply",
				data:{
					theuser:theuser,
					deskid:deskid,
					message_reply:reply
				},
				success: function(replyz)
				{
					if(replyz == 1)
					{
						see_message_toreply(deskid);
						$("textarea[name=reply_fields]").val('');
						
						var div = $('#main_scrol_reply');
						div.delay(5000).scrollTop( div.get(0).scrollHeight );//scroll to bottom not work after loading the data, this is my problem
					}
				}
			});
		}
		else
		{
			$('#pop_msg').fadeOut('fast').html("Reply too short.").removeAttr("class").attr('class','errormsg').fadeIn('fast').delay(5000).fadeOut('fast').draggable({revert: false,containment: 'body',handle:'#pop_msg'});	
		}
	}
}