title: Why is GetMetricData returning an empty set of values?
body: <p>Using the JS AWS SDK and passing the following parameters:</p>
  
  <pre><code>{
    "StartTime": 1548111915,
    "EndTime": 1549321515,
    "MetricDataQueries": [
      {
        "Id": "m1",
        "MetricStat": {
          "Metric": {
            "MetricName": "NetworkOut",
            "Namespace": "AWS/EC2",
            "Dimensions": [
              {
                "Name": "InstanceId",
                "Value": "i-[redacted]"
              }
            ]
          },
          "Period": 300,
          "Stat": "Average",
          "Unit": "Gigabytes"
        }
      }
    ]
  }
  </code></pre>
  
  <p>This is the output:</p>
  
  <pre><code>[
    {
      "Id": "m1",
      "Label": "NetworkOut",
      "Timestamps": [],
      "Values": [],
      "StatusCode": "Complete",
      "Messages": []
    }
  ]
  </code></pre>
  
  <ol>
  <li><p>The query closely matches the sample request found at <a href="https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_GetMetricData.html#API_GetMetricData_Examples" rel="nofollow noreferrer">https://docs.aws.amazon.com/AmazonCloudWatch/latest/APIReference/API_GetMetricData.html#API_GetMetricData_Examples</a></p></li>
  <li><p>I am sure that the instance is a valid instance that has definitely had NetworkOut traffic during that date range.</p></li>
  </ol>
  
  <p>What reason could account for the lack of elements in <code>Values</code> array?</p>