Sort for different date depending of the contentType

[Giovanni Luca Ulivo]

Hi guys. i have a problem with a sort  in a ElasticSearch query. 

I need to sort by a different date depending of the contentType.

 this is the query :

{ 

   "size":9,

   "from":0,

   "sort" :{ 

       "_script" : {

            "script" :{

              "lang": "painless",

               "source":" if(doc.contentType.value=='IntrEvents'){doc.modDate.value.millis }                                       else if(doc.contentType.value=='IntrPressReleases' ){                         doc.modDate.value.millis } "},

        "type" : "number",

        "order" : "desc"

    }

},

"query":{

    "bool":{

        "should":[

            {"bool":{"must":[{"terms":{"contenttype":["intrPressReleases"]}}]}},

            {"bool":{"must":[{"terms":{"contenttype":["intrEvents"]}}]}}

            ]

            }}

}

if i use the modDate fiels the response is ok. if i use a specific date of the contentType 

( for example : if(doc.contentType.value=='IntrEvents'){doc.startDate.value.millis } else if(doc.contentType.value=='IntrPressReleases' ){ doc.datePressReleases.value.millis }    ) i receive an error : 

ElasticsearchStatusException[Elasticsearch exception [type=search_phase_execution_exception, reason=all shards failed]]

The 2 date  are setted to be required and indexed in the contentType. 

why i dont'see the value of this fields in the doc map of script ?