I have uploaded a PowerPivot workbook to the PowerPivot Gallery and am now attempting to use it as a data source for PerformancePoint, but I keep received the following error when making the connection in Dashboard Designer: "An error occurred connecting to this data source. Please check the data source for any unsaved changes and click on Test Data Source button to confirm connection to the data source." The file is not open and the Test Data Source button is grayed out. What is the proper URL syntax? I'm not sure if the URL is the problem either. Any help would be appreciated.
too late a response but anyway
i resolved the issue by increasing the max limit for excel services to required level. By default its 10MB and the powerpivot files are much larger.
SharePoint Central Administration, and go to Application Management > Manage Service Applications > ExcelServiceApp > Trusted File Locations and click on the appropriate Address. Under the Workbook Properties section you will see a Maximum Workbook Size