Hi!
The only way to fix this is to add extra lines to the header.php file. The search will not work if the jquery and other scripts are loaded in the footer, because the $(document).ready event is never fired.
Add exactly the following lines to the header:
<script src="http://testing.quehaypahacer.com/wp-content/plugins/ajax-search-pro/js/jquery.ajaxsearchpro.min.js"></script>
<style>
.probox .loading {
border: none !important;
opacity: 1 !important;
padding: 0 !important;
position: static !important;
z-index: 10100;
}
</style>