Customise default slice

Hi,
I'm new to flexmonster so I'm sure I'm doing something silly but I can't get it to display a custom slice on page load.
Here's what I'm doing:

1. I took the generic initialisation from a JSFiddle
2. Customised it to use my license etc
3. Loaded the data into flexmonster, re-arranged it to my liking and clicked save
4. Opened the resulting .xml file and copied the slice object
5. Pasted into the generic initialisation

When I load the page, it shows the default slice and I'm not quite sure why:

var pivot = new Flexmonster({
	container: "pivotContainer",
	componentFolder: '/flexmonster/',
	toolbar: true,
	licenseKey: "MY KEY",
	report: {
		dataSource: {
			dataSourceType: "json",
			filename: "/src/reports/dataset",
		},
		"slice": {
			"rows": [{
					"uniqueName": "GROUP A"
				},
				{
					"uniqueName": "GROUP B"
				},
				{
					"uniqueName": "GROUP C"
				}
			],
			"columns": [{
				"uniqueName": "[Measures]"
			}],
			"measures": [{
					"uniqueName": "COL1",
					"aggregation": "sum"
				},
				{
					"uniqueName": "COL2",
					"aggregation": "sum"
				},
				{
					"uniqueName": "COL3",
					"aggregation": "sum"
				},
				{
					"uniqueName": "COL4",
					"aggregation": "sum"
				},
				{
					"uniqueName": "COL5",
					"aggregation": "sum"
				},
				{
					"uniqueName": "COL6",
					"aggregation": "sum"
				}
			]
		}
	}
});

As I said, I'm sure I'm doing something silly, but there's no console errors and everything else seems to be working correctly so I'm not quite sure what - any help would be appreciated!

 
Thanks