If you're using the same code as the sample's, I guess that the the cause of the problem is in this line in the function GetDataset().
//Get the first id datasetId = results["value"][0]["id"];
It would always return the first datasetId instead of the one created in the code if there're more datasets alreay existing.
Change the line to lines
//Get the first id //datasetId = results["value"][0]["id"]; var datasets = results["value"]; foreach (var ds in datasets) { //return the id of the first salesmarketing dataset if (ds["name"] == "SalesMarketing") { datasetId = ds["id"]; break; } }