grafana weird target field

dashboard.json

{
  "rows": [
    {
      "panels": [
        {
          "datasource": "$awsAccount",
          "targets": [
            {
              "dimensions": {
                "LoadBalancerName": "$product-$environment-$role-01"
              },
              "hide": false,
              "metricName": "UnHealthyHostCount",
              "namespace": "AWS/ELB",
              "period": "",
              "refId": "A",
              "region": "$region",
              "statistics": [
                "Maximum"
              ],
              "target": "sumSeries(perSecond(some.unrelated.metric.from.another.panel.with.no.effect.here))",
              "textEditor": false
            }
          ]
        }
      ]
    }
  ]
}