You may see a "Call to Excel Services failed" error when trying to perform a scheduled data refresh using PowerPivot for SharePoint on a workbook in SharePoint 2013 that has a Power Query connection to a data source. At this time, Power Query is not supported by SharePoint 2013 on-premise. It is only supported by Power BI for Office 365 (SharePoint Online).
http://blogs.msdn.com/b/powerbi/archive/2014/05/02/scheduled-data-refresh-for-power-query.aspx
As a workaround, you can connect to the data source without using Power Query by creating a data connection using PowerPivot. To determine whether or not the workbook currently has a Power Query data connection, look at the connection string in Excel by going to Data > Connections > Properties > Definition. If the Provider is Microsoft.Mashup.OleDb.1, this indicates that the data connection was made using Power Query.
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