Can't set time field from log entry (Kibana 3)

Hi, I want to configure the time field from a log entry. I have a param "date" in object message from json formatted as Kibana date "yyyy-mm-ddT:hh:mm:ss.sssZ" and also separated in the object tags. I would like charts and tables will use tags.date for drawing instead of _source.date.

This is a table entry, see tags.date is built from message. I can sort by my tag date:

{
  "_index": "logs-xxxxxxx-2015.10.19",
  "_type": "log",
  "_id": "AVCAEy5v-ZsPos8fIh-J",
  "_score": null,
  "_source": {
    "date": "2015-10-19T12:29:13.214Z",
    "message": "2015/10/19 08:29:11 [event:xxxxxx][date:2015-10-19T08:29:11.324Z][user_id:xxxxx][country_code:xx][phone_number:xxxxxxxxx][flow_type:xxxx][flow_sub_type:xxxx][message:null]",
    "tags": {
      "app": "xxxxxxxxx",
      "date": "2015-10-19t08:29:11.324z",
      "serv": "webserver",
      "phost": "xxxxxxx",
      "datacenter": "xxxx",
      "source": "xxxxxxxxxx",
      "dept": "xxxx",
      "message": "null",
      "short_source": "mercury.log",
      "flow_sub_type": "xxxxx",
      "country_code": "xxxx",
      "log_type": "application",
      "flow_type": "xxxxxx",
      "user_id": "xxxxxx",
      "scope": "null",
      "host": "xxxxxxx",
      "phone_number": "xxxxx",
      "persistent": "true",
      "event": "xxxxxx",
      "gav": "master"
    }
  },
  "sort": [
    "2015-10-19t08:29:11.324z"
  ]
}

.
.
But when I set the tags.date for a chart, it gets blank.
.

.

I also configured timepicker as tags.date in dashboard general configuration but it didn't work.
.

.
Unfortunately I don't have control of the interface which communicate my API with Kibana. I able to configure my api or kibana dashboard. Suggestions?

I apologise in advance if I have been unclear.
Thanks