i have a ajax login form. i'm able to use the username in another page, but i also want to use the level of the user after they login. i can't seem to get the $level variable to pass on to the other pages.

Code:
<script language="javascript">


$(document).ready(function()
{
	$("#login_form").submit(function()
	{
		//remove all the class add the messagebox classes and start fading
		$("#msgbox").removeClass().addClass('messagebox').text('Validating....').fadeIn(1000);
		//check the username exists or not from ajax
		$.post("ajax_login.php",{ user_name:$('#username').val(),password:$('#password').val(),rand:Math.random(), level:$('#level').val() } ,function(data)
        {
		  if(data=='yes') //if correct login detail
		  {
		  	$("#msgbox").fadeTo(200,0.1,function()  //start fading the messagebox
			{ 
			  //add message and change the class of the box and start fading
			  $(this).html('Logging in.....').addClass('messageboxok').fadeTo(900,1,
              function()
			  { 
			  	 //redirect to secure page
				 document.location='add2.php';
			  });
			  
			});
		  }
		  else 
		  {
		  	$("#msgbox").fadeTo(200,0.1,function() //start fading the messagebox
			{ 
			  //add message and change the class of the box and start fading
			  $(this).html('Your login detail do not match...').addClass('messageboxerror').fadeTo(900,1);
			});		
          }
				
        });
 		return false; //not to post the  form physically
	});
	//now call the ajax also focus move from 
	$("#password").blur(function()
	{
		$("#login_form").trigger('submit');
	});
});
</script>

form processing
//get the posted values
$user_name=htmlspecialchars($_POST['user_name'],ENT_QUOTES);
$pass=md5($_POST['password']);
$level=$_POST['level'];


//now validating the username and password
$sql="SELECT user_name, password, level FROM user WHERE user_name='".$user_name."'";
$result=mysql_query($sql);
$row=mysql_fetch_array($result);

//if username exists
if(mysql_num_rows($result)>0)
{
	//compare the password
	if(strcmp($row['password'],$pass)==0)
	{
		echo "yes";
		//now set the session from here if needed
		$_SESSION['u_name']=$user_name;
		$_SESSION['level']=$level;
	}
	else
		echo "no"; 
}
else
	echo "no"; //Invalid Login