PivotGridV2 Local Binding cannot to change measure name

Hi 

I used the PivotGridV2 from Local Binding of data source. I want to change the measure name at demo sample, for example:  Sum change to Sumass, than I found error from browser  for "format error".  How to change the measure name of local binding data source?

 measures: {
                                "Sumass": { field: "Revenue", format: "{0:c}", aggregate: "sum"},
                                "Average": { field: "Revenue", format: "{0:c}", aggregate: "average" }
                            }
                        }
                    },
                    columns: [{ name: "Year", expand: true }, { name: "Sector" } ],
                    rows: [{ name: "Country", expand: true }],
                    measures: ["Sumass", "Average"]

James