cannot get cloudwatch metric data with getMetricStatistics

Question

I currently have a node application where I am trying to use the getMetricStatistics function of the AWS Cloudwatch sdk to retrieve data from a metric into my application.

In order to troubleshoot this I have run the listMetrics function as follows:

var params = {
        MetricName: 'Open',
        Namespace: 'AWS/SES',
    };
    cloudwatch.listMetrics(params, function(err, data) {
        if (err) console.log(err, err.stack); // an error occurred
        else     console.log(data);           // successful response
    });

After running the above code, I get output written via console.log:

After this I try to run the getMetricStatistics function as follows:

    var cloudwatch = new aws.CloudWatch({apiVersion: '2010-08-01'});
    var params = {
        EndTime: new Date(2022,1,31), /* required */
        MetricName: 'Open', /* required */
        Namespace: 'AWS/SES', /* required */
        Period: '3600', /* required */
        StartTime: new Date(2022,1,27), /* required */
        Dimensions: [
          {
            Name: 'test-open-key', /* required */
            Value: 'test-open-value' /* required */
          }
          /* more items */
        ],
        Statistics: [
          'Average',
          /* more items */
        ]
      };
      cloudwatch.getMetricStatistics(params, function(err, data) {
        if (err) console.log(err, err.stack); // an error occurred
        else     console.log(data);           // successful response
      });

However, the output of the above code is as follows, showing no datapoints:

I have based my input parameters based on what I got from listMetrics, and in my console I can see the following graph, meaning there should be at least one datapoint retrieved on the 29th January.

Would anyone be able to advise on what I'm doing wrong/any further avenues for troubleshooting?