Why doesn't this mapping work?

mapping

curl -XPUT "http://localhost:9200/contests/" -d'
{
  "settings": {
    "index.number_of_replicas": 0,
    "index.number_of_shards": 1,
    "index.refresh_interval": -1
  },
  "mappings": {
    "contest": {
      "properties": {
        "contestant": {
          "type": "nested",
          "properties": {
            "id": {
              "type": "string",
              "index": "not_analyzed"
            },
            "data": {
              "type": "nested",
              "properties": {
                "timing": {
                  "type": "integer"
                },
                "expectedTiming": {
                  "type": "integer"
                }
              }
            }
          }
        }
      }
    }
  }
}'

query

curl -XGET "http://localhost:9200/contests/_search" -d'
{
   "aggs": {
      "myResults": {
         "nested": {
            "path": "contestant"
         },
         "aggs": {
            "per_contestant": {
               "terms": {
                  "field": "id"
               },
               "aggs": {
                  "timingInfo": {
                    "nested": {
                      "path": "contestant.data"
                    },
                    "aggs": {
                     "sum": {
                        "field": "contestant.data.timing"
                     }                      
                    }
                  }
               }
            }
         }
      }
   },
   "explain": true
}'