Authentication issue in Elasticsearch with Shield

Question

I've installed Shield plugin for ES and configured users with roles. But when I try to index some data with configured user, I always received this error:

[2015-11-22 10:31:58,795][INFO ][rest.suppressed          ] /app-nginx-stats-2015-11-22/http-stats Params: {}
ElasticsearchSecurityException[unable to authenticate user [es_admin] for REST request [/app-nginx-stats-2015-11-22/http-stats]]
        at org.elasticsearch.shield.support.Exceptions.authenticationError(Exceptions.java:39)

I know about issue with @ in password so I've changed it to 123456 - doesn't help. I also executed esusers list on ES node and I see my users in the output.

So what other common mistakes could lead to "unable to authenticate user" error? Or how can I debug such issues?