It looks more like to me that the file is missing, or blocked by .htaccess or on server level.
When I clicked on the link, it gives this error:
Access to this resource on the server is denied!
That means the file most likely exists, but the access is denied. This is 99% related to a .htaccess rule, as the error page is printed with a nice template. One other thing you can check is the file persmissions. It should be “644”, but you can try “755” or “775” to check if it's permission related problem. 644 however should work without problems.
The file is accessible correctly if it gives “-1” as the output when you click on the link. Just like the one on the demo page: http://wp-dreams.com/demo/wp-ajax-search-pro/wp-content/plugins/ajax-search-pro/ajax_search.phpBest,
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