保持窗口切换打开以显示和查看错误消息AJAX，JQuery，PHP

I am having an issue trying to keep a cretin window toggled opened after AJAX retrieves data, to show a proper message to denote weather or not the user has logged in or not. My Javascript is as follows:

function validLogin(){
var username=$('#username').val();
var password=$('#password').val();
    var dataString = 'username='+ username + '&password='+ password;
$("#flash").show();
$("#flash").fadeIn(400).html('<img src="images/loading.gif" width="32px" height="32px" />');
$.ajax({
    type: "POST",
    url: "login.php",
    data: dataString,
    cache: true,
    success: function(result){
    var result=trim(result);
    $("#flash").hide();
    if(result=='correct'){
        $("fieldset#signin_menu").show(); // <-- This will not work!
}else{
    $("#errorMessage").html(result);
}

}

After I get the informatoin the window should stay open; however, the page refreshes and the window closes. This is an onclick event once you press "Sign In". A window will pop down. Here is the code for that window popping down:

$(document).ready(function() {

$(".signin").click(function(e) {          
    e.preventDefault();
            $("fieldset#signin_menu").toggle();
            $(".signin").toggleClass("menu-open");
    });

    $("fieldset#signin_menu").mouseup(function() {
            return false
    });

    $(document).mouseup(function(e) {
    if($(e.target).parent("a.signin").length==0) {
            $(".signin").removeClass("menu-open");
    $("fieldset#signin_menu").hide();

    }

});

Is there a better work around for this? Am I doing this wrong?

use this jquery instead

 $(document).ready(function() {               
 $("fieldset#signin_menu").show(function() {
 $(".signin").toggleClass("menu-open");
 });
 });

$("fieldset#signin_menu").mouseup(function() {
        return false
});

$(document).mouseup(function(e) {
if($(e.target).parent("a.signin").length==0) {
        $(".signin").removeClass("menu-open");
$("fieldset#signin_menu").hide();

}

});