[jQuery] setTimeout() not working

[sarahzizo]

Hello all
i am losing my mind here what is wrong with this code the setTimeout
is not working.
I am creating a messaging system and i send and recieve data but i
want it to appear on another window of the browser
here is the code

        $(document).ready(function(){
                $("form#chatform").submit(function(){
                        $.get("db.php",{
                                                message: $("#msg").val(),
                                                action: "postmsg",
                                        }, function(data) {
                                $("#msg").empty();
                                addMessages(data);
                        });
                        return false;
                });
        });

                function addMessages(data)
                {
                                $("#t1").prepend(data);
                }
                function updateMsg() {
                        $.get("db.php",
                         function(data) {
                         addMessages(data);
                        });
                        setTimeout('updateMsg()', 4000);
                }

And this is the  php code
<?php
// Configuration
$dbhost = "localhost";
$dbuser = "root";
$dbpass = "root";
$dbname = "crisis";


header("Cache-Control: no-cache");

$dbconn = mysql_connect($dbhost,$dbuser,$dbpass);
mysql_select_db($dbname,$dbconn);

$name = $_GET['name'];
$user2 = $_GET['user2'];
$user = $_GET['user'];
$msg = $_GET['message'];

foreach($_GET as $key => $value)
{
        $$key = mysql_real_escape_string($value, $dbconn);
}

if(@$action == "postmsg")
{
        mysql_query("INSERT INTO Messages (Msg_body)
                                VALUES ('$msg')") or die(mysql_error());
}

$messages = mysql_query("SELECT From_user,Msg_body,Date_Time
                                                 FROM Messages
                                                 WHERE Msg_ID = 
LAST_INSERT_ID() ") or die(mysql_error());

        while($message = mysql_fetch_array($messages))
                {
                                echo "<tbody id='tbody1'>
                                          <tr class='highlight'>
                                          <td width='30' align='center'
style='color:royalblue'>"."&#8226;"."</td>
                                      <td width='70' 
align='left'>".$message["Date_Time"]."</td>
                                          <td width='600' 
align='left'>".$message["User_name"]."</td>
                                          <td width='600' align='left'></td>
                                          <td width='100' 
align='left'>".$message["Grp_abr"]."</td>
                                          <tr class='highlight'>
                                          <td></td>
                                          <td 
colspan='4'>".$message["Msg_body"]."</td></tr>
                                          </tbody>";
                           }

?>