Elasticsearch does not return jsonp
Are you prior to v2.0? Looks like they removed jsonp in 2.0 (elastic.co/guide/en/elasticsearch/reference/2.2/…).
Alsopretty%%callback%% doesn't look right, the %%callback%% macro usually needs to be the value of name (like onload=%%callback%%). The element replaces %%callback%% with the name of a global function that is generated for you.