Unauthorized access to internal API

[Francesco]

Using search box in a website page (eg. http://mtbfriuli.com/eng/guide.html) appears this error message: 

Unauthorized access to internal API. Please refer to https://support.google.com/customsearch/answer/4542055

Could it be related to API 2.0? How can it be solved? 

Thanks

Francesco 

In page header: 

        <!-- Google Search -->
        <script>
          (function() {
            var cx = '00000000000000000:aaaaaaaaaaaaaaaaa';
            var gcse = document.createElement('script');
            gcse.type = 'text/javascript';
            gcse.async = true;
            gcse.src = 'https://cse.google.com/cse.js?cx=' + cx;
            var s = document.getElementsByTagName('script')[0];
            s.parentNode.insertBefore(gcse, s);
          })();
        </script>

[amadzay]

hi, how did you resolve this problem please?