I am using page 28 of this doc for reference: https://resources.docs.salesforce.com/200/latest/en-us/sfdc/pdf/bi_dev_guide_saql.pdf

I need to change the time zone in the step. I am trying to use the computeExpression action to handle it. Here is the code I tried: 

     "CreatedDate_Hour_3": {
                "datasets": [
                    {
                        "id": "0Fb32000000TVRzCAO",
                        "label": "Case_Article_Survey",
                        "name": "Case_Article_Survey",
                        "url": "/services/data/v38.0/wave/datasets/0Fb32000000TVRzCAO"
                    }
                ],
                "isFacet": true,
                "isGlobal": false,
                "action": "computeExpression",
                "parameters": {
                    "source": "CreatedDate_Hour_3",
                    "mergeWithSource": true,
                    "computedFields": [
                        {
                            "name": "CreatedDateNew",
                            "type": "Date",
                            "format": "MM/dd/yyyy",
                            "saqlExpression": "toDate(CreatedDate_Hour_3 - 8*3600)"
                        }
                    ]
                },
                "query": {
                    "pigql": "q = load \"Case_Article_Survey\";\r\nq = group q by 'CreatedDateNew';\r\nq = foreach q generate 'CreatedDateNew' as 'CreatedDateNew', count() as 'count';\r\nq = order q by 'CreatedDateNew' asc;\r\nq = limit q 2000;",
                    "measures": [
                        [
                            "count",
                            "*",
                            "count"
                        ]
                    ],
                    "measuresMap": {},
                    "autoFilter": true,
                    "groups": [
                        "CreatedDateNew"
                    ]
                },
                "selectMode": "single",
                "type": "aggregateflex",
                "useGlobal": false,
                "visualizationParameters": {
                    "options": {}
                }
            },


I am getting an error that says **"This widget can't be displayed because of a problem with the underlying step, CreateDate_Hour_3."**