I am using this code to signup a user and check if the user exists.

When I enter an exists user my PHO correctly returns "exist" but my jquery is showing it in a normal alert not the DevExpress alert as if it's an error 

is there any issue in my if (data == "exist")

this is my code:

1. $.ajax({
2.     type: "POST",
3.     url: 'https://www.mydomain.com/ws/signin_user.php',
4.     async: true,
5.     data: formData,
6.     dataType: "json",
7.     processData: false,
8.     contentType: false,
9.     success: function (data) {
10.         $("#loadPanelSignup").dxLoadPanel("instance").option("visible", false);
11. 
    
12.         if (data == "exist") {
13.             DevExpress.ui.dialog.alert('The email address already exist!', 'Attention').done(function () {
14.                 return;
15.             });
16.         }
17.         else {
18.             DevExpress.ui.dialog.alert('We have sent you an email.', 'Thank you').done(function () {
19.                 XoomPage.app.navigate({ view: "activate", user_id: data.UserDetails[0].user_id, user_guid: data.UserDetails[0].user_guid, activation_guid: data.UserDetails[0].activation_guid, activation_check_guid: data.UserDetails[0].activation_check_guid, email_address: data.UserDetails[0].email_address }, { root: true });
20.             });
21.         }
22.     },
23.     error: function (xhr, status, error) {
24.         alert(xhr.responseText);
25.     }
26. });
    

Thanks,

Jassim