The OrderReferenceId C01-9737628-XXXXXX is invalid


Hi All!
I’m trying to “GetOrderReferenceDetails” using dotnet SDK but I’m getting this response: “The OrderReferenceId C01-9737628-XXXXXX is invalid”.
I grabbed the AmazonOrderReferenceId like so:
onOrderReferenceCreate: function (orderReference) { var id = orderReference.getAmazonOrderReferenceId(); }

which returns something like C01-9737628-XXXXXX.

The environment is sandbox.

This is the code I’m using to get the detail on server side:
var getOrdDetailReq = new GetOrderReferenceDetailsRequest()

        var getOrdDetailRes = client.GetOrderReferenceDetails(getOrdDetailReq);

Am I missing something?