Hi Armend,
The problem is due to modifications you did on the wp-content\plugins\ajax-search-pro\includes\views\asp.shortcode.custom_fields.php
There is a variable $x_in that is incremented on several different occasions ($x_in++) with your modifications, however it is used on the server side to check the field names. It should be left as it is (only incremented once), otherwise the script is not able to verify the field names. I recommend using a different method there, maybe another variable, if you want to make such modification.