You are effectively requesting from another domain.
The request is coming from http://incomebrokers.com while you are loading http://www.incomebrokers.com (with www in it). Because the url with and without www are seen as different URL's you need to make sure to append www in both cases.
There is another workaround. In your PHP file, place this right under your <?php
tag.
<?php header('Access-Control-Allow-Origin: *'); ?>
This will allow requesting from 'other' domains.