Cannot update custom object (Quickblox)

Question

I'm having a problem updating a custom object. Weird thing is that one object (let's call it object #1) is updated fine, while the other (object #2) returns "Not authorized to update application_settings object".

Object #2 belongs to the Account Owner user (I'm talking about the value of "User ID" field), object #1 belongs to another user. Want to note that the problem occurs even when I authorize as the account owner user:

QBASessionCreationRequest *extendedAuthRequest = [[QBASessionCreationRequest alloc] init];
extendedAuthRequest.userLogin = @"login";
extendedAuthRequest.userPassword = @"password";
[QBAuth createSessionWithExtendedRequest:extendedAuthRequest delegate:self];

Here's what happens when I try to update object #2:

PUT http://api.quickblox.com/data/application_settings/51d07504535c12a1ef000dd6.xml?push%5Bprofile_images_ids_180px%5D=987654321
headers:{
    "QB-SDK" = "iOS 1.5.2";
    "Qb-Token" = xxxxxxxxxxxxxxxxx;
    "QuickBlox-REST-API-Version" = "0.1.1";
}
parameters:
raw body:

RestResponse:

<QBASIHTTPRequest: 0xabca400>
headers:{
    "Access-Control-Allow-Origin" = "*";
    "Access-Control-Request-Method" = "*";
    "Cache-Control" = "no-cache";
    Connection = Close;
    "Content-Length" = 191;
    "Content-Type" = "application/xml; charset=utf-8";
    Date = "Tue, 09 Jul 2013 17:03:07 GMT";
    "QuickBlox-REST-API-Version" = "0.1.1";
    Server = "nginx/1.0.15";
    Status = "403 Forbidden";
    "X-Rack-Cache" = "invalidate, pass";
    "X-Request-Id" = 732c8f2002b8bd03241d4c88288557fd;
    "X-Runtime" = "0.043522";
    "X-UA-Compatible" = "IE=Edge,chrome=1";
}
body:<?xml version="1.0" encoding="UTF-8"?>
<errors type="array">
  <error>
    <code nil="true"/>
    <message>Not authorized to update application_settings object</message>
  </error>
</errors>