I am using the code below to sign in user with ajax and it's working fine when I just user window.location in the success but when I tried to give a condition to check the querystring ["redirect"] it will just stop on the loading animation and do noting.

what's wrong with this code please?

2. $(document).ready(function(){
3.     $(function() { $( "#btnSignin" ).button(); });
4. 
   
5.     $('#btnSignin').click(function()
6.     {
7.         $('#waiting').show();
8.         $('#frmLogin').hide();
9. 
   
10.         $.ajax
11.         ({
12.             type : 'POST',
13.             url : '<?php echo $_SESSION["domain_name"]; ?>loginmember',
14.             dataType : 'json',
15.             data: { email : $('#txtEmailAddress').val(), pwd : $('#txtPassword').val() },
16.             success : function(data)
17.             { 
18.                 if (data.error === true)
19.                 $('#waiting').hide();
20.                 // $('#frmLogin').show();
21.                 if (_GET['redirect']) { window.location = '<?php echo $_SESSION["domain_name"]; ?>biz'; }
22.                 else { window.location = '<?php echo $_SESSION["domain_name"]; ?>memberhome'; }
23.             },
24.             error : function(XMLHttpRequest, textStatus, errorThrown)
25.             {
26.                 $('#waiting').hide();
27.                 $('#frmLogin').show();
28.             }
29.         });
30. 
    
31.         return false;
32.     });
33. });